Abstract: Supercapacitors are emerging as a compelling energy storage solution, enhancing superior power density, extended charge-discharge cycles, and improved safety compared to traditional batteries. Developments in supercapacitor technology, especially in the innovative design and refinement of electrode materials, represent a substantial leap forward in addressing the world's growing energy storage needs. In the pursuit of advancing electrode materials, the study and utilization of 2D materials and their derivatives have revealed significant potential. These materials have emerged as highly promising candidates due to their mechanical strength, high surface area, and exceptional electrochemical properties. Among these, transition metal oxides stand out as a cutting-edge class of materials with highly favorable applications in supercapacitor electrodes. Their abundant resources and low production costs are significant advantages for large-scale supercapacitor production. This chapter offers an in-depth exploration of supercapacitor technology, emphasizing the latest breakthroughs in electrode materials and their effects on performance. It also underscores the pivotal role of transition metal oxides in realizing high-capacity and efficient energy storage systems. Finally, the chapter outlines the existing limitations and challenges associated with the development and use of transition metal oxides. It also delves into potential solutions and future directions, offering a comprehensive overview of the strategies needed to overcome these obstacles and advance the use of transition metal oxides in energy storage technologies.

Abstract: Modern energy systems have explored the potential of supercapacitors (SCs) as a solution to issues regarding low power and energy densities of batteries and capacitors. Our research demonstrates the fabrication of a composite comprising polypyrrole (PPy), multi-walled carbon nanotubes (MWCNTs), and nickel cobaltite (NiCo2O4) for high-performance SC. The hydrothermal and oxidative polymerization techniques were employed to hybridize NiCo2O4@MWCNT with PPy. X-Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were performed to analyze phase, redox species, and structural parameters that contribute to the improved electrochemical performance and stability of the system. Field Emission Scanning Electron Microscopy (FESEM) and Energy-Dispersive Spectroscopy (EDS) reveal the morphology and purity of the samples. The synergistic interaction among the individual components resulted in elevated performance, owing to an enhanced hybrid storage mechanism. The metal-carbon interactions between polymeric chains and metal centres from NiCo2O4, combined with conductive pathways, significantly enhanced the storage capacity. The mixed electrolyte used in fabrication also plays a key role in this enhanced mechanism. The fabricated symmetric device achieved a storage capacity of ∼224 F/g at 1 A/g, with 75% capacitance retention after 10,000 discharge cycles at 1000 mV/sec, and an energy density of ∼45 Wh/kg at a power density of ∼600 W/kg. Overall, the proposed hybrid composite is a suitable candidate for high-performance supercapacitors.

Abstract: Carbon dioxide (CO₂) conversion is a crucial challenge in addressing global warming and climate change. Non-thermal plasma reactors present a promising alternative to thermal catalysis for converting CO₂ into CO and O₂. In this study, a dielectric barrier discharge (DBD) plasma reactor operated under ambient conditions, demonstrating both scalability and efficiency. The introduction of a photocatalyst into the plasma reactor enhanced plasma discharge properties, while the active photons, electrons, and vibrationally excited molecules within the plasma further boosted the photocatalyst's activity. Notably, the incorporation of halogen-doped g-C₃N₄ significantly improved CO₂ conversion compared to the no-packing condition. A maximum CO₂ conversion of approximately 11% was achieved using Br/g-C₃N₄ at an applied voltage of 22 kV. Additionally, halogen doping enhanced CO selectivity and energy efficiency. During discharge, electron energy facilitated excitation, dissociation, and recombination processes. Furthermore, the use of photocatalysts in the DBD reactor may help reduce coke formation, improving reaction stability.

Abstract: Cs2AgInCl6 is an important lead-free double perovskite valued for its structural stability, potential in photocatalysis, and CO2 reduction, but its practical application is limited by intrinsically UV-dominated absorption. Through strategic defect engineering, this work demonstrates that Cu2+ doping effectively extends its absorption into the visible region. By combining theoretical calculations with experimental investigations, the study reveals how Cu2+ incorporation modifies the electronic structure and enhances the optical absorption. These results provide clear insights into the photophysical processes of the material, which are essential for improving its catalytic performance. A comprehensive DFT investigation reveals that the doping of Cu2+ prefers the substitution at the Ag+ site and results in the introduction of impurity states adjacent to the VBM. Experimental positron annihilation lifetime spectroscopy indicates the formation of defects with positron trapping characteristics upon Cu2+ doping. Variable temperature emission behavior is well explained by the Arrhenius equation with the activation energy of 93.3 meV and significant electron-phonon coupling strength indicated by the large value of the Huang-Rhys parameter (S = 19.46). Cu2+-doped Cs2AgInCl6 was investigated for photocatalytic applications. The Cu2+-doped sample exhibited 98% degradation of crystal violet dye. Furthermore, the material was explored for nonthermal plasma-assisted CO2 hydrogenation. An enhanced CO2 conversion efficiency was observed with Cu doping. We believe that our findings significantly enhance the understanding of the Cu2+-doped Cs2AgInCl6 system and provide valuable insights into its structure-property relationships for catalytic applications. 

Abstract: Due to the growing need for cost-effective, environmentally friendly energy storage devices, research on advanced electrode materials for supercapacitors (SCs) is becoming increasingly important. A ternary hybrid nanomaterial of PANI, MWCNT, and ZnCo2O4 was developed and investigated as an active material. This hybrid composite material was prepared by combining hydrothermally synthesized ZnCo2O4 with purchased MWCNT and PANI via an in situ chemical oxidative polymerization. The structural characterization results showed that a ternary composite was successfully formed. XRD results of the material showed characteristic peaks of MWCNTs (∼26°), PANI (∼20°), and ZnCo2O4 (∼36°). FESEM and EDS results also confirmed the synthesis of a PANI-MWCNT-ZnCo2O4 composite. Additionally, XPS analysis of the material revealed active electrochemical centers in the metal oxides for Faradaic charge storage. BET analysis of the composite showed a significant increase in surface area (∼82.6 m2/g). The energy density of the fabricated symmetric device was 66.8 Wh/kg, with a power density of 900 W/kg and a specific capacitance of 334F/g at 1.5 A/g. In addition, a high coulombic efficiency of ∼ 95.48 % was achieved, while ∼ 81 % of the device’s initial capacitance was retained after 10,000 charge–discharge cycles. The enhanced electrochemical performance is attributed to the synergistic interaction among PANI, MWCNTs, and ZnCo2O4, highlighting the composite’s potential as an efficient and reliable electrode material for next-generation energy storage applications.

Abstract: This paper reports the preparation and characterization of a silk-glycerol composite-based, biocompatible, optically transparent, and flexible substrate. Blending glycerol with silk not only eliminates the brittleness of pure silk films but also enhances flexibility and long-term mechanical stability. Its applicability in the electrochemical detection of E. coli bacteria on a screen-printed electrode system is a testament to the robustness of the substrate. To improve the sensitivity and selectivity of E. coli detection, the working electrode is modified with amine-functionalized WO3 nanorods. The developed flexible biosensor platform selectively detects the targeted E. coli bacteria sample, even in mixed bacterial cultures and fungal strains, with an ultra-low detection limit of 0.15 CFU/mL and at the same time, it has a wide detection range starting from 0.15 CFU/mL to 1.5 × 104 CFU/mL. The repeatability, stability and specificity studies in real samples affirmatively indicate its potential for usage in clinical applications.

Abstract: The increasing demand for reliable and efficient energy-storage systems has driven continued interest in advanced materials capable of supporting rapid and stable charge storage. Supercapacitors (SC) can provide pathways to meet such requirements with enhanced energy density and an improved life cycle. This study presents the fabrication and analysis of a hybrid comprising polyaniline (PANI), MWCNT, and vanadium pentoxide (V2O5), synthesized via oxidative polymerization and a hydrothermal approach. The synthesized hybrid ternary composite (HTC) was characterized using structural, morphological, and electrochemical analysis. The integration of MWCNT provides continuous pathways for efficient electron transport and enhanced ion-diffusion kinetics. The redox-active behavior of V2O5 contributed as an additional pseudocapacitive component to the overall storage mechanism. Electrochemical characteristics demonstrate a pseudocapacitive behavior with a specific capacitance of 295.67 F/g at 1 A/g and ∼91% capacitance retention after 5000 cycles. Also, the device exhibited an energy density of 59.13 Wh/kg at a power density of 0.6 kW/kg. These results demonstrate that interactions among individual components significantly enhance hybrid charge-storage performance. Overall, the synthesized PANI/MWCNT/V2O5 can be a promising hybrid material for next-generation energy storage devices.

Abstract: In this study, a series of mixed transition metal dichalcogenides, Mo 1-x W x S 2 (x = 0.3, 0.5, and 0.7), were synthesized via a one-pot hydrothermal method to engineer controllable 2D-2D heterostructures through a substitution strategy. The incorporation of W into the MoS 2 lattice induces basal-plane disorder, expanded interlayer spacing, and a high density of lattice defects in the resulting Mo 1-x W x S 2 systems. XRD, Raman, and XPS analyses collectively confirm the emergence of a mixed-metallic 1T/2H phase and distortion in the S-Mo/W-S stacking, validating the formation of a hetero-layered 2D-2D architecture across all compositions. Electron microscopy reveals a clear transition from aggregated MoS 2 nanopetals to an increasingly intertwined and interconnected 2D-sheet-like network, with the Mo 0.5 W 0.5 S 2 composition exhibiting the most optimized heterolayer-assembly and enhanced surface area. Benefiting from this engineered 2D-2D framework, Mo 0.5 W 0.5 S 2 delivers a high specific capacitance of 558.6 F g -1 at 1 A g -1, nearly double that of pristine-MoS 2 . A symmetric-supercapacitor device fabricated using this optimized electrode achieves an energy density of 24.1 Wh kg -1 at a power density of 866.6 W kg -1 and retains 88.4% capacitance with 100% coulombic efficiency after 10,000 cycles. These features collectively enable fast ion-transport in the system, thereby enhancing the electrochemical performance of the developed supercapacitor device.

Abstract: Photoelectrochemical (PEC) water splitting has attracted significant interest owing to its ability to produce hydrogen (H2) as a clean fuel using semiconductors, thereby reducing CO2 emissions, climate change, and fossil fuel consumption. In this work, we fabricated an efficient heterostructure S-TiO2/BiSbS3/ZnS photoanode using sol–gel, chemical bath deposition (CBD), and successive ionic layer adsorption and reaction (SILAR) methods. In a neutral aqueous electrolyte, the photoanode exhibited a photocurrent density of 3.5 mA.cm−2 at 1.23 V vs RHE and a 1.01% solar to hydrogen (STH) efficiency at 0.15 V vs RHE. Under alkaline conditions, an increased photocurrent density of 6.4 mA.cm−2 at 1.23 V vs RHE and an STH of 2.8% at 0.28 V vs RHE was observed, significantly outperforming the corresponding binary and single-component systems, and this was attributed to hole scavenging from sacrificial (S22− and SO32– ions) reagents in alkaline media. The ternary photoanode also demonstrated the best current density and photostability for over 3600 s compared to the binary photoelectrodes. Density functional theory (DFT) was employed to investigate the charge-transfer behavior in the heterojunctions of n–n-type S-TiO2/ZnS and n–p-type S-TiO2/BiSbS3 and their suitability as photoanodes for the oxygen evolution reaction (OER). Work function calculations and charge density difference investigations showed a positive vacuum-level shift of 5.57 eV in S-TiO2/BiSbS3/ZnS, an n–p–n-type Z‑scheme heterojunction developed by introducing ZnS into S-TiO2/BiSbS3. The ternary photocatalyst was found to show Z-scheme electron transfer, wherein photogenerated electrons from ZnS recombine with photogenerated holes of S-TiO2/BiSbS3, and the oxidation potential of ZnS is preserved as the photogenerated holes stay in the valence band of ZnS, leading to higher photoelectrochemical activity. Mechanistic investigation on the OER coordinates validated that the higher photoelectrochemical activity of the S-TiO2/BiSbS3/ZnS heterostructure is due to the stabilization of OER intermediates and a thermodynamic OER overpotential of 1.06 V. 

Abstract: Numerous materials have been explored by the scientific community for constructing efficient and durable energy storage devices. High-entropy oxides (HEOs) are considered as promising class of materials, especially for battery and supercapacitor applications. Due to their unique electrochemical properties, enhanced stability, good electrical conductivity, and synergetic effect of multiple elemental compositions, these materials show excellent performance in the above applications. The incorporation of various noble metals like Pd, Pt, and Ru further enhances the redox activity, resulting in enhanced specific capacitance and rate capability. These important properties of noble-metal-based high-entropy oxides (NM-HEOs) material offers a distinct advantage for energy storage applications. This chapter offers insights into synthesis, characterization, and key properties of this particular class of material for battery and supercapacitor applications, highlighting the current state and future perspective. 

Abstract: This study aims to develop improved radar-absorbing material (RAM) by investigating the performance of hydrogenated acrylonitrile butadiene rubber (HNBR) composites reinforced with milled carbon fibre (MCF). MCF was incorporated into HNBR at different loading percentages, starting from 0 to 10 parts per hundred rubber (PHR). The fibres were characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and found to have a highly crystalline structure with high purity. The resulting composites were assessed starting with their cure characteristics and mechanical properties, followed by electromagnetic performance in the 8–12 GHz frequency range. Results show that at 4 Phr MCF loading yielded a 30% increase in tensile strength compared to unfilled HNBR, while the dielectric constant peaked at 10 Phr loading. Notably, a maximum return loss of –13 dB at 10 GHz with a 2 GHz bandwidth was achieved at 7 Phr MCF loading. Strain-induced crystallization was observed, contributing to the enhanced mechanical properties. The study revealed a trade-off between mechanical and electromagnetic properties at different MCF loadings. In conclusion, this work demonstrates the effectiveness of HNBR-MCF composites as RAM, providing valuable insights into filler-content-property relationships and opening avenues for developing multifunctional elastomeric materials for electromagnetic applications in defence systems. 

Abstract: Calcium ferrite (CaFe2O4, CFO) was synthesized from red mud (RM) via a hydrothermal method and applied as a particle electrode in a three-dimensional electrochemical (3DE) system for treating tetracycline (TC)-containing water. Structural and surface analyses confirmed that the RM-derived CFO possessed properties comparable to those of chemically synthesized CFO. When used in the 3DE system, an increase in catalyst dose, initial TC concentration and applied voltage tended to enhance the removal of water-borne TC and a mildly acidic to neutral pH favored the TC removal. The CFO-RM electrode exhibited excellent catalytic activity, achieving >99 % TC removal within 60 min under optimized conditions (catalyst dose at 0.5 g L⁻1, initial TC concentration at 50 mg L⁻1, applied voltage at 10 V, and solution pH at 6). While the CFO-RM had a capacity to adsorb TC, adsorption only played a minor role in the removal of water-borne TC and chemical oxidation was the key driver in the treatment process. Hydroxyl radical (•OH) and superoxide radical (•O2⁻) were identified as the dominant reactive oxygen species that drove the TC degradation process. Toxicity assessment revealed that the 3DE system developed in this study was highly effective in de-toxifying water-borne TC. 

Abstract:

Abstract: A new class of hybrid materials, combining the properties of conducting polymers (CPs), transition-metal oxides (TMOs), and carbon nanostructures, can enhance capacitance, rate capability, and cyclic stability of the supercapacitor (SC) devices. The current study present the synergistic integration of polyaniline (PANI), multi-walled carbon nanotubes (MWCNTs), and NiCoFeO4 inverse spinel oxide based hybrid composite is developed by in-situ polymerization and hydrothermal technique. X-ray diffraction pattern confirmed the crystalline phases present in the samples. FEMSEM micrograph investigated the structural and morphological characteristics of individual and hybrid composite which revealed that MWCNT and NiCoFeO4 embedded uniformly within the PANI matrix to form a well interconnected porous network, thereby improving ion pathways and introducing enormous redox active sites. Furthermore, to investigate the various oxidation states and chemical environment or functionalization is characterized by X-ray photoelectron spectroscopy (XPS). Furthermore, BET analysis demonstrated the average pore size and surface area of PANI decorated MWCNT/NiCoFeO4 hybrid composite and it is estimated ~16.7 nm and 48 m2/g, respectively. The TC-based device exhibited a specific capacitance of 281.75 F/g at 1 A/g along with an energy density of 56.35 Wh/kg, and a power density of 600 W/kg. The TC device exhibited capacitance retention of ~76% after 10,000 cycles. The synergistic interaction between individual components causes enhanced electrochemical performances, highlighting the suitability of PANI decorated MWCNT/NiCoFeO4 hybrid composite for next-generation SC applications.

Abstract: Copper-based photoelectrocatalysts are promising for cathodic reactions such as hydrogen evolution (HER) and oxygen reduction reaction (ORR); however, their performance is limited by fast charge recombination and poor stability due to photocorrosion. In this work, we report a cascade photoelectrocatalytic system constructed of metal-organic framework (MOF)-templated multidimensional heterointerfaces, enabling stepwise charge transfer and enhanced carrier separation. A series of Cu-Bi binary metal-organic frameworks with systematic compositional tuning of Cu:Bi ratios was transformed into the corresponding Cu-Bi heterostructures via a controlled chemical treatment followed by thermal treatment, yielding binary CuBi2O4/Bi2O3 (M-CBO/BO) and ternary Cu2O/CuBi2O4/CuO (M-CBO/CO) heterojunctions. The optimal Cu:Bi = 2:1 composition yields a ternary M-CBO/CO architecture delivered a total photocathodic current density of J = -9.4 mA cm⁻2 at -0.3V vs RHE with incident photon-to-current conversion efficiency (IPCE) of 22.5% at 360 nm, governed by cascade charge transfer, uniquely balances charge separation, and suppresses charge recombination compared to other systems. In contrast, the binary M-CBO/BO system operates via a Z-scheme charge-transfer pathway. The photoinduced reduction activity arises from a bias-driven transition from ORR at positive potentials to HER at negative potentials. A systematic study revealed correlations among phase composition, morphology, stable bifunctional photoelectrochemical activity, and the optical properties of the engineered photocathodes, shedding light on the underlying charge-transfer mechanisms.

Abstract: In this work, the conduction and dielectric relaxation properties of Ca2+-substituted Ba0.8Sr0.2-xCaxTiO3 compositions, x = 0 (BST), 0.06 (BSCT06), and 0.08 (BSCT08), are investigated in relation to their microstructure using impedance spectroscopy. The Nyquist plots of impedance spectroscopy exhibit two semicircles in all compositions, representing relaxation mechanisms resulting from the contributions of grain interiors and grain boundaries. Moreover, a trail of an additional semicircular arc corresponding to the interfacial effect is observed at high temperatures in the Ca-modified compositions (BSCT06 and BSCT08). The large semicircular arc and corresponding prominent relaxation peak in the frequency-dependent impedance suggest the dominant influence of the grain boundary on the electrical properties of all the compositions. The Ca2+ substitution in parent composition BST leads to a reduction in the large semicircle arc and its relaxation peak of BSCT06 and BSCT08, resulting in decreased resistance from grain boundaries. It indicates an overall decrease in the insulating nature of the Ca-modified BST composition, which is further validated by their enhanced DC conductivity. This occurs due to the increased mobility of oxygen vacancies in the Ca-substituted compositions. This observation is supported by the reduction in activation energies of the Ca-substituted materials BSCT06 (1.13 eV) and BSCT08 (0.83 eV) with respect to pure BST (1.56 eV), calculated from the relaxation peak of grain boundaries, A similar decreasing trend was observed from the AC conductivity study, with activation energy values of 1.06 eV (BST), 0.98 eV (BST06), and 0.76 eV (BST08). In addition to electrical properties, the compositions also exhibit photocatalytic functionality. Among the compositions, 6 mol% Ca-modified composition (BSCT06) displayed the best photocatalytic activity of Methylene blue (MB), with 97% efficiency and a reaction rate constant of 0.0147 min−1. Also, energy harvesting potential of these ceramics incorporated with PVDF matrix have been investigated which showed a comparatively high output voltage of 10.6 V was obtained for BSCT06/PVDF at a constant force of 24 N. These results have been linked to microstructural variations, specifically a grain size and a reduced band gap. 

Abstract: Need for high-performance, efficient, and economical devices for next-generation energy storage technologies have led researchers to explore supercapacitors (SC) as alternative. A novel hybrid composite (HC)-based device comprising polyaniline (PANI), multiwalled carbon nanotubes (MWCNTs), zinc oxide (ZnO), and nickel oxide (NiO) was developed via in situ oxidative polymerization and hydrothermal processing for high-performance SC applications. The composite integrates the pseudocapacitive behavior of transition metal oxides with the superior conductivity of PANI and MWCNT. Structural and morphological analyses confirmed a highly interconnected hybrid network, where PANI formed a conductive polymeric matrix, MWCNTs facilitated rapid electron transport, and ZnO/NiO nanoparticles provided abundant redox-active sites. Electrochemical experiments conducted with the HC-based device exhibit a specific capacitance of 319.52 F g−1 at 1 A g−1, surpassing individual components. The HC-based device delivered an energy density of 63.90 Wh kg−1 at a power density of 0.6 kW kg−1, retaining 78% capacitance after 10,000 cycles at 12 A g−1. This enhanced performance, confirmed by electrochemical impedance spectroscopy analysis showing low charge-transfer resistance and efficient ion diffusion, underscores the synergistic interaction among its constituents. The composite's outstanding electrochemical characteristics establish it as a promising candidate for next-generation, high energy density, long cycle life SCs. 

Abstract: Molecular-modification-based hydrogel precursors have been established as a potential approach for the generation of hierarchical porous carbon material. This paper utilized chitosan as a carbon precursor to produce insoluble gels through the introduction of an aqueous NaOH solution, followed by a one-step carbonization method to prepare three-dimensional porous carbon structures. This material comprises numerous interconnected cosmic web-like networks that facilitate the migration of the electrolyte within the carbon material. The electrochemical energy storage performances of hydrogel-derived hierarchical porous cosmic weblike carbon (HGC) electrodes were measured in various aqueous electrolytes, including 1 M H2SO4, 1 M KOH, and 1 M Na2SO4. In these aqueous electrolytes, the HGC electrode, in a three-electrode configuration, demonstrated high specific capacitances of 475 F g–1, 312 F g–1, and 79 F g–1, respectively, at a current density of 0.5 A g–1. The symmetric supercapacitor, using 1 M H2SO4 electrolyte, exhibited a specific capacitance of 244 F g–1, an energy density of 30.6 Wh kg–1, and a power density of 476 W kg–1 at an operating voltage of 1.0 V. This electrode exhibited a capacitance retention of 98% even after 5000 charge–discharge cycles at a current density of 5 A g–1, demonstrating exceptional cycling stability. The results reveal that supercapacitors exhibit distinct capacitive characteristics across different electrolytes, with optimal electrochemical performance observed in 1 M H2SO4. These findings underscore the potential of HGC as a versatile electrode material for advanced energy storage applications, highlighting its adaptability across various electrolytes and exceptional performance in acidic environments.  

Abstract: Spinels such as NiCo2O4 (NCO), known for their variable oxidation states and electrocatalytic properties, hold significant potential as nanozymes but are often limited by a lower number of active sites and poor conductivity. Herein the activity of NCO was enhanced by doping Cu in place of Ni during the glucose (Glu) sensing. NCO and Cu-doped NCO (Cu-NCO) nanosheets were synthesized via facile co-precipitation method. Cu doping increased the surface area and porosity, as confirmed by Brunauer–Emmett–Teller (BET) analysis, and enhanced oxygen vacancies, as evidenced by X-ray photoelectron spectroscopy (XPS). Controlled Cu doping enabled precise tuning of the electronic structure and electrocatalytic activity of nanozymes. The Cu-NCO demonstrated superior Glu oxidation activity at lower potential than undoped NCO and showed highest sensitivity of 2133.80 µA mM-1 cm-2 in 10 µM to 2.5 mM Glu range, and 818.59 µA mM-1 cm-2  in the 2.5 to 9 mM range. Conversely, NCO exhibited low sensitivities of 1254.08 and 362.96 µA mM-1 cm-2. The best Glu sensing of Cu-NCO was attributed to the improved charge transfer, electrical conductivity and enriched redox chemistry due to the incorporation of Cu2+. Density functional theory (DFT) simulations highlight improved conductivity and charge transfer with Cu-NCO, supporting the experimental findings. This study presents a cost-effective approach to designing high-performance nanozymes for developing analytically proficient sensors. 

Abstract: Waterborne bacterial contamination remains a pressing global health concern, demanding point-of-care (POC) devices for rapid and efficient on-site detection. High costs, long processing times and reliance on sophisticated equipment limit conventional methods. Thus, this study proposes the fabrication of a low-cost, disposable paper-based electrochemical biosensor for the effective and selective detection of gram-negative bacteria. The developed biosensor was modified with g-C3N4/amine-functionalised carbon dots composite to boost signal transduction and offer stable immobilisation of TLR-4/MD-2 bioreceptor, which detects explicitly the lipopolysaccharide layer of gram-negative bacteria samples. The developed paper-based biosensor revealed an excellent analytical performance with remarkable specificity and achieved a low theoretical limit of detection of 0.66 CFU/mL and 0.88 CFU/mL for E. coli and P. aeruginosa, respectively, across a wide dynamic range of 1.5 to 1.5 × 10⁵ CFU/mL. Furthermore, the biosensor demonstrated good stability, reproducibility and ability to attain a satisfactory low LOD in the spiked tap and pond water samples. Moreover, the simple disposability of the paper electrodes lowers the cross-contamination issues and ensures the safety of the environment. Collectively, this work introduces a sustainable, low-cost, and portable biosensing platform that effectively integrates nanomaterial for enhanced transduction with receptor-based specificity, offering significant potential for early diagnosis of waterborne bacterial contamination and advancing public health protection through POC application.

Abstract: A design-directed process is used to prepare Cu-Cu2O-CuO/carbon composite particles of ∼1–2 μm in size. The composite particles are constituted by flower-petal-like features of Cu-Cu2O-CuO supported by carbon. They are composed of amorphous carbon (with C═O and surface-adsorbed −OH groups), as well as metallic Cu and cationic Cu (i.e., Cu in both Cu+ and Cu2+ states), which enables them to control fungal growth and nutrition in plants. The amounts of Cu and carbon in the composite particles are 20.19 at. % and 62.72 at. %, respectively. Antifungal activity and micronutrient supply of the composite particles are evaluated using a mycelial growth inhibition assay and through standard plant growth responses. Moderate zeta potential values of different test solutions of the composite particles in DI water help balance the stability and deposition of the composite particles onto fungal hyphae and seed surfaces, enabling their ultralow-dose efficacy in controlling fungal growth and stimulating plant growth. 

Abstract: Zero-dimensional (0D) organic-inorganic hybrid metal halides (OIHMHs) are excellent luminescent semiconductor materials due to their unique opto-electronic properties. The phase transition-induced emission modulation of the OIHMHs under external stimuli, such as heat and pressure, has been demonstrated. Recently, the modulation of self-trapped exciton (STE) emission by fine lattice distortion has also attracted considerable attention. However, the role of these structural modulations in exciton recombination pathways remains poorly explored. Here, we report the laser-induced photoluminescence intensity enhancement in 0D OIHMHs, using 1-butyl-1-methylpiperidinium copper bromide [(Bmpip) 2 Cu 2 Br 4 ] microcrystals (MCs). The photoluminescence intensity of the MCs increases significantly with a change in the emission color from a green-red dual emission to a yellow emission. Correspondingly, the emission spectrum changes from the distinct bimodal green-to-red profile to a broad yellow band. The results of excitation wavelength-dependent, time-resolved, and temperature-controlled fluorescence, as well as single-crystal X-ray diffraction studies, suggest that the changes from the green-to-red dual emission, delayed by the STE trapping and de-trapping process, to the yellow emission occur by laser-induced Cu-Cu coordination changes that suppress the exciton trapping process. These findings provide insights into the impact of photoexcitation on OIHMHs and provide a novel approach for optical modulation to optimize them for photonic applications.

Abstract: Emerging contaminants (ECs), predominantly introduced by anthropogenic activities, have become a growing concern due to their detrimental impacts on human health and the environment. Their presence in water bodies and the environment has been consistently recognized as a worldwide problem, and their abatement is a top priority for the supply of contaminant-free water. However, the removal of these ECs is very challenging. Many biological and physicochemical treatment technologies have been investigated to treat ECs from water and wastewater, yet complete abatement of ECs remains challenging. Advanced oxidation processes (AOPs) are widely noticed in EC treatment due to their high oxidation efficiency and no secondary pollution. Photocatalysis and ozonation are efficient AOP methods used for treating ECs, which are technically simple yet more effective and achieve fast degradation with no addition of chemicals. This chapter highlights the advancements in the state-of-the-art photocatalytic ozonation process for the treatment of waterborne ECs with a focused approach on a comprehensive evaluation of the photocatalytic ozonation process involving the key operational and procedural factors that influence the efficiency of the process, along with mechanistic insights. Furthermore, advantages, key challenges, bottlenecks, and prospects of photocatalytic ozonation technology have been discussed in this chapter, consolidating the up-to-date information into one comprehensive source and establishing a solid basis for future studies on progress and decision-making. 

Abstract: For the past decades, great efforts have been made to beneficially utilize red mud, a hazardous waste material from alumina refining. These include recovery of valuable metals, use as feedstock for making construction materials, and various environmental applications. There have been numerous review articles that evaluated and analyzed the published literature on the adsorption application of red mud for treating contaminated water. However, little effort has been made to synthesize the existing knowledge on red mud application as the feedstock for making coagulants, catalysts, and conditioners despite that there has been increasing published reports on these aspects. To fill this knowledge gap, a systematic review was conducted by initially screening relevant journal articles published within the last 10 years (2015–2025) and subsequently critically analyzing and evaluating the selected articles. The results showed that there was a clear trend that the published work on catalyst application increased over time, especially in the recent 5 years while the published work on coagulation and conditioner applications fluctuated. Red mud-derived catalysts were applied in different types of advanced oxidation processes, mainly including photocatalysis, conventional Fenton oxidation, photo-Fenton oxidation, electro-Fenton oxidation and persulfate oxidation. Through this systematic review, the challenges for red mud applications in making catalysts, coagulants and conditioners were identified and recommendations for further research are made accordingly. 

Abstract: Alzheimer's disease (AD) is a neurodegenerative disorder due to the formation of amyloid-β plaques and neurofibrillary tangles that lead to brain abnormalities. It is commonly observed in elderly people worldwide. Due to these diseases, patients suffer from dementia and social and economic issues. Several drugs are commercially available for the treatment of AD; however, the issue of passing the blood–brain barrier (BBB) is a hurdle for AD therapy and leads to several side effects. The use of nanoformulations of AD drugs with several polymers, liposomes, and carbon materials has the advantage of treating the disorder more effectively. However, most nanoparticles based on the polymeric system have the disadvantage of being unable to target the central nervous system (CNS) and cannot cross the BBB. In the current chapter, we discuss the synthesis of chitosan-based polymeric nanoparticles, formulation with AD drugs, and biological application and advantages of the developed system. This nanotechnological approach will create a new era of AD treatment. Many effective drugs like Rivastigmine, curcumin, piperine, thymoquinone, and 17-estradiol loaded with chitosan nanoparticles show better efficacy in AD.

Abstract: Semiconductor nanomaterials, such as cadmium, lead, and mercury chalcogenides, as well as lead halide perovskites, exhibit excellent optical, electronic, photonic, and photovoltaic properties, making them promising for applications in solar cells, LEDs, and X-ray photodetectors. However, heavy metals in these nanomaterials raise concerns about their use in devices and the recycling and disposal of such devices. Therefore, developing greener luminescent materials is crucial for sustainable optoelectronic and photovoltaic technologies. We report a colloidal chemical method for engineering brilliantly luminescent titanium nitride (TiN) quantum dots showing tunable optical bandgap (1.8–2.2 eV) and multicolor photoluminescence. We demonstrate the TiN quantum dot structure and properties using HRTEM, SEM-EDX, XRD, XPS, Raman spectroscopy, and steady-state and time-resolved fluorescence spectroscopy, confirming their size, morphology, chemical composition, crystalline structure, bandgap, and luminescence properties. This research presents luminescent TiN quantum dots as promising substitutes for metal chalcogenides and lead halide perovskites in sustainable electrooptical and photovoltaic technologies.

Abstract: Providing clean water globally is a high priority issue. In this book chapter, we have discussed the different types of metal oxides like zinc oxide (ZnO), titanium dioxide (TiO2), iron oxide (Fe2O3), and magnesium oxides (MgO) preparation, characterization, and their applications towards the removal of organic, inorganic pollutants and bacteria/fungus from wastewater to produce potable water. We have presented different purification methods such as adsorption, photocatalysis, and advanced oxidation (AOP) in detail based on the literature. We have also added advantages and disadvantages of every metal oxide and its use in particular purification methods. In the end, we also discussed the challenges, future perspectives, and conclusions.c 

Abstract: A Z-scheme electron transfer mechanism, coupled with plasmonic effects, is highly desirable for achieving enhanced photocatalytic performance. Graphitic carbon nitride (g-C3N4)-based Z-scheme photocatalytic systems have been widely reported due to their cost-effectiveness, photo-chemical stability, and environmental sustainability. In this study, we report the fabrication of a novel Z-scheme heterojunction photocatalyst, Ag-decorated FeCo2O4/g-C3N4 (Ag@FCO-PCN), synthesized via an integrated approach involving auto-moisturization, polycondensation, ultrasonication, and photoreduction techniques. Electron paramagnetic resonance (EPR) analysis was employed to investigate atomic vacancies in pure FeCo2O4 and g-C3N4, which play a crucial role in enhancing charge carrier separation. The synthesized photocatalysts were extensively characterized using a suite of optical and physicochemical techniques. The photocatalytic performance of the ternary Ag@FCO-PCN nanocomposite was evaluated through aqueous phase degradation of methylene blue (MB), used as a model organic pollutant. Under visible light irradiation and in the presence of potassium persulfate (PS), the ternary composite exhibited a photo-Fenton-like degradation mechanism, achieving nearly 99% MB removal within 3 hours. Among the tested materials, Ag@FeCo2O4/g-C3N4 demonstrated the highest charge separation efficiency compared to pristine g-C3N4, FeCo2O4, and the binary FeCo2O4/g-C3N4 composite. Scavenger experiments confirmed the generation of reactive species including SO4 •⁻, h⁺, O2 •⁻, and OH•, with SO4 •⁻ playing a dominant role in the degradation pathway, thereby supporting the proposed Z-scheme mechanism. The ternary composite was easily recovered using magnetic separation and exhibited excellent cyclic stability and reusability, as confirmed by post-reaction characterizations. This study presents new insights into the development of stable, efficient, and reusable metal nanoparticledecorated metal oxide-based photo Fenton like heterogeneous catalysts for advanced photocatalytic applications.

Abstract: Li-containing ternary vanadates are known for their remarkable structural diversity and tunable physical properties, making them attractive for advanced functional applications. In this study, we present a systematic investigation of Co2+ and Ni2+ -doped LiZnVO4 to elucidate their structural transitions, optical behaviour, and potential for energy-efficient coating technologies. A clear miscibility gap is observed in intermediate compositions, indicating limited solid solubility between the two end members. The local lithium environments were probed using magic angle spinning 7Li solid-state nuclear magnetic resonance spectroscopy, providing direct evidence for the incorporation of two paramagnetic dopant ions into the crystal lattice. At low dopant concentrations, the 7Li isotropic peak intensity increases due to paramagnetic relaxation enhancement, whereas higher concentrations lead to characteristic peak broadening. CIELAB colour space shows systematic colour tuning with increasing dopant concentration: green → brown → black for Co-doping and light greenish yellow → yellow → brown for Ni-doping. Importantly, the doped LZVO-0.02Ni and LZVO-0.02Co compositions exhibited high NIR solar reflectance of 85.7% and 65.2% respectively, in the wavelength range 700-2200 nm, enabling effective solar heat management. The combination of phase-selective doping, tunable colour properties, and strong NIR solar reflectivity positions these materials as promising candidates for next-generation cool pigments in sustainable coating applications.

Abstract: Recycling mixed-color PET plastic waste into monomers is challenging due to dye/pigment effects on catalyst stability and monomer purity yet crucial for a circular plastic economy. To achieve this, we developed a colorant-tolerant and highly reusable magnetic MnOx/Fe3O4 nanocatalyst (calcined at 400 °C, MnOx/Fe3O4-4) for the efficient methanolysis of mixed-color PET bottles to produce a value-added dimethyl terephthalate (DMT) monomer. The Mn3+/Mn4+ species, uniformly dispersed on the surface of morphology-controlled Fe3O4, are the primary active sites in the cleavage of PET polymer toward DMT monomer. The innate magnetic strength of Fe3O4 played a key role in improving the stability of the MnOx/Fe3O4-4 catalyst in colored PET solution and easy recovery of the catalyst after the reaction. This dual functionality (Mn3+/Mn4+ and magnetic Fe3O4) bolstered efficient methanolysis of various PET plastic materials, including industrial PET scrap, transparent PET, and mixed-color PET bottles (transparent, blue, and green), with a 96–98% isolated yield of DMT at mild reaction conditions. The PET methanolysis process was scaled up to 5 g using both transparent and mixed-color (blue and green) PET bottles. The MnOx/Fe3O4-4 nanocatalyst exhibited excellent reusability across various colored PET plastics with 86–87% isolated DMT yields even after seven cycles, offering promising practical solutions for the PET plastic recycling industry. 

Abstract: This study aims to develop improved radar-absorbing material (RAM) by investigating the performance of hydrogenated acrylonitrile butadiene rubber (HNBR) composites reinforced with milled carbon fibre (MCF). MCF was incorporated into HNBR at different loading percentages, starting from 0 to 10 parts per hundred rubber (PHR). The fibres were characterised using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and found to have a highly crystalline structure with high purity. The resulting composites were assessed starting with their cure characteristics and mechanical properties, followed by electromagnetic performance in the 8-12 GHz frequency range. Results show that at 4 Phr MCF loading yielded a 30% increase in tensile strength compared to unfilled HNBR, while the dielectric constant peaked at 10 Phr loading. Notably, a maximum return loss of -13 dB at 10 GHz with a 2 GHz bandwidth was achieved at 7 Phr MCF loading. Strain-induced crystallization was observed, contributing to the enhanced mechanical properties. The study revealed a trade-off between mechanical and electromagnetic properties at different MCF loadings. In conclusion, this work demonstrates the effectiveness of HNBR-MCF composites as RAM, providing valuable insights into filler content-property relationships and opening avenues for developing multifunctional elastomeric materials for electromagnetic applications in defence systems.

Abstract: Gold nanoparticles (AuNPs) are of significant interest due to their unique properties and applications in biomedicine. While hyaluronic acid (HA) has been used to modify pre-formed AuNPs, its thiolated derivative (HA−SH) has been less explored for the direct synthesis and stabilization of AuNPs. This study investigates the use of thiolated hyaluronic acid as a key component in the synthesis of AuNPs. A series of HA-AuNPs (HA-AuNP1-4) were synthesized by reacting HA-SH with HAuCl4 at different mass ratios. The resulting nanoparticles were characterized using UV-Vis spectroscopy, scanning/transmission electron microscopy (SEM/STEM), X-ray photoelectron spectroscopy (XPS), photon cross-correlation spectroscopy (PCCS), and zeta potential measurements. The chemical transformations of the thiol ligand were studied using NMR spectroscopy. The morphologies and sizes of AuNPs depended on the HA-SH-to-HAuCl4 ratio, ranging from icosahedral and triangular particles (≥146 nm) to quasi-spherical particles with a bimodal distribution (6–7 nm and 45–60 nm). XPS confirmed the presence of metallic gold (Au0) and a Au−S bond, while NMR and XPS revealed the partial oxidation of thiol groups to sulfonic acid. Zeta potential measurements showed that lower HAuCl4 concentrations resulted in higher negative charge (up to −41.5 mV), enhancing colloidal stability. This work demonstrates a versatile approach to the synthesis of hyaluronic acid-based gold nanomaterials with tunable properties for potential biomedical applications 

Abstract: The quantum of nutrients supplied for efficient Rosemary plant growth and high-quality essential oil (EO) yield is relatively high, posing an environmental hazard. Therefore, developing nutrient management strategies that reduce environmental impact while maintaining or enhancing Rosemary plant growth, bio-fortification, secondary metabolite content, and EO yield is imperative. In this line, this work reports a simple mechanical milling strategy that enables low-dosage foliar application of nanosized macro-nutrient and micro-nutrient particles for extraordinary Rosemary plant growth, bio-fortification, enhanced secondary metabolites, and high-quality EO yield even at a considerably lower nutrient supply. Even for a much lower dosage than the recommended dosage, a considerable increase in the total plant weight and in nitrogen (N), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) content in plant shoots, in excellent correlation with their enhanced availability on the surface of the nanosized nutrient particles, is achieved. More importantly, an increase in the concentration of 1,8-cineole (a key metabolite in EO and the quality descriptor of EO) in EO extracted from the plants cultivated using nanoscaled nutrients at much lower inputs is achieved. The enhanced concentration of 1,8-cineole is attributed to the increased presence of Zn, Mn, and Cu, which elicit specific pathways for synthesizing 1,8-cineole in plants. This work offers a simple, scalable, sustainable alternative strategy to conventional high-nutrient-input agricultural practices. 

Abstract: Water pollution remains a critical environmental challenge, necessitating the development of cost-effective treatment methodologies. This study investigates sustainable alternatives to conventional adsorbents, focusing on the synthesis and application of Blast Furnace Slag (BFS)-supported biochar. The composite adsorbent was synthesized through pyrolysis of sewage sludge and wood sawdust combined with BFS for the removal of 4-nitrophenol (4-NP). The composite adsorbents were characterized for their physical and chemical properties. Adsorption studies on 4-NP were performed under various operating conditions such as pollutant dosage, pH, and temperature. The composite demonstrated a maximum adsorption capacity of 12 mg/g at pH 6, using an adsorbent dose of 1.0 g/L, an initial 4-NP concentration of 20 mg/L, a contact time of 90 min, and a temperature of 25 °C. The adsorption process was evaluated using five linear isotherm models, with Langmuir fitting best and pseudo-second-order kinetics governing the mechanism. Economic analysis revealed that the production cost of 1 kg of adsorbent was 3.35 USD. Additionally, the sustainability of the adsorbent was assessed using the sustainability footprint methodology, along with a sustainability score-based approach to examine its impact on all 17 Sustainable Development Goals (SDGs). The study findings support the use of industrial and residential waste materials as viable resources for producing cost-effective adsorbents to combat various water pollutants. 

Abstract: In this study, we explore the potential of Vigna Mungo (L) Hepper (black gram skin, BGS), an agricultural byproduct, for synthesising high-quality graphite through a catalytic graphitisation process. Using a nickel-catalysed method, we successfully transformed BGS- derived carbon into highly ordered graphite at 1300 °C (BG-1300), with further surface area enhancement achieved via KOH activation (BG-1300-KOH) including X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HR-TEM), confirmed the formation of highly ordered graphite with a high degree of graphitisation (62.9%) and crystallite size (9.69 nm). Electrochemical evaluations demonstrated the potential of BGS-derived graphite as an anode material for lithium-ion batteries (LIBs) and lithium-ion hybrid capacitors (Li-HCs). The BG-1300-KOH sample exhibited a reversible discharge capacity of 610 mAh g⁻¹, outperforming commercial graphite (410 mAh g⁻¹) and pristine BG-1300 (380 mAh g⁻¹). The extent of Na-ion intercalation indicates the degree of disorder in carbon. In this study, as the carbonization temperature increases, the intercalation capacity progressively decreased, reflecting a transition toward more ordered, graphitic carbon. Furthermore, a Li-HC device fabricated with BG-1300-KOH as the anode and nitrogen-phosphorous-doped hard carbon (BGAC-NP) as the cathode achieved a maximum energy density of 175 Wh kg⁻¹ and a power density of 25,000 W kg⁻¹, surpassing many reported carbon-based Li-HC devices. This study highlights the feasibility of converting agricultural waste into high-performance graphite, offering a sustainable pathway for energy storage applications while addressing environmental concerns associated with biomass disposal.

Abstract: The demand for trans-1,3,3,3-tetrafluoropropene [HFO-1234ze(E)] as a next-generation, low-global-warming-potential (GWP) refrigerant is rising due to international restrictions on high-GWP refrigerants like chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). Catalytic dehydrofluorination of HFC-245fa offers a viable synthesis route for the production of HFO-1234ze(E), but the catalyst degradation under harsh acidic conditions remains a major challenge. In this study, a highly stable γ-Al2O3 supported catalyst was developed for efficient dehydrofluorination with vanadium species exhibited the highest activity among the screened metal ions Ni2+, V5+, Zn2+, La3+, Fe3+, Mn2+ and Cu2+.The optimized 15wt% V2O5/γ-Al2O3 catalyst, prepared without oxalic acid assistance, exhibited strong metal-support interactions and demonstrated superior catalytic performance achieving ~95% HFC-245fa conversion. The catalyst activity increased from 1.3 to 2.1 μmols-1 gcat-1 due to the formation of in-situ VOFx species generated through the interaction between V2O5 and HF, as confirmed by NH3-TPD and XPS analysis. The catalyst also ~81% selectivity towards HFO-1234ze(E) at 350 °C. Noteworthy, the catalyst maintained a stable performance up to 74 h, without significant deactivation. Overall, these results highlight the importance of rational metal selection, loading optimization, and interface engineering in developing robust catalysts for industrial hydrofluoroolefin production. 

Abstract: A lead-free Na0.85Ag0.15Nb0.95Mg0.05O3 (AM-NN) polycrystalline ceramic was synthesized using the conventional solid-state reaction method, and its structural, dielectric, impedance, and optical properties were thoroughly investigated. X-ray diffraction (XRD) and Rietveld refinement of AM-NN confirmed that the material adopts a perovskite-type orthorhombic structure with the P21ma space group. Introducing oxygen vacancies through AgO resulted in spectral changes observed in Raman spectroscopy and Photoluminescence. Dielectric and complex impedance measurements, taken from 102–106 Hz and room temperature to 500 °C, exhibited non-Debye behavior. AM-NN presented a reduced band gap of 3.12 eV compared to pure NaNbO3 (NN) (3.4 eV) as obtained from UV-vis spectroscopy. AM-NN demonstrated a superior photocatalytic dye degradation percentage of 99% methylene blue (MB), 95% crystal violet (CV) and 60% congo red (CR) at 300 min with the rate constant (k) of 0.0128 min−1 (MB), 0.0138 min−1 (CV) and 0.0027 min−1 (CR), respectively. PEC water splitting showed that the photoanode fabricated with AM-NN exhibits enriched photocurrent density (1.11 mA cm−2). XRD showed no secondary phase after dye degradation, indicating the system's reusability. A detailed investigation into the electrical properties and photocatalytic mechanism was provided to account for the observed improvements in dye degradation and water splitting applications. 

Abstract: The global transition toward clean and sustainable energy sources necessitates advancing efficient technologies for green hydrogen production. Photoelectrochemical water splitting (PEC-WS) is a promising solar-to-fuel conversion approach that directly utilizes solar energy to produce hydrogen. This study explores the fabrication and performance of novel heterojunction photoelectrodes based on TiO2, Mn-doped CdS (Mn:CdS), and copper zinc tin sulfide (CZTS). Mn:CdS offers tunable band structures and enhanced visible light absorption, while CZTS contributes strong light harvesting and chemical stability. TiO2 with its wide bandgap and excellent charge transport properties, serves as an electron-conducting layer that facilitates charge separation and suppresses recombination. We designed and tested four heterojunction configurations TiO2/CdS (TC), TiO2/Mn:CdS (TMC), TiO2/CdS/CZTS (TCCZ) and TiO2/Mn:CdS/CZTS (TMCCZ). Among these, the TMCCZ photoelectrode exhibited highest photocurrent density (Jsc = 4.0 mA cm−2 at 1.23 VRHE) and an applied bias photon-to-current efficiency (ABPE ∼3.58 % at 0.28 VRHE) in 0.1 M aq. Na2SO4 electrolyte (pH = 6.87). Superior performance is attributed to synergistic band alignment, extended light absorption into the near-infrared (NIR) region, prolonged photogenerated carrier lifetime (4.05 ns), and reduced interfacial charge-transfer resistance (Rct = 114.3 Ω) as verified by UV–Vis spectroscopy, photoluminescence decay, and electrochemical impedance spectroscopy (EIS). The H2 evolution rate was found to be 13.35 mmol h−1 cm−1 in 0.1 M aq. Na2SO4 electrolyte. Furthermore, incorporating robust materials, strategic surface passivation, and optimized electrode architecture contributed to improved stability and minimized recombination losses. These findings underscore the synergistic benefits of TMCCZ heterojunction system and its potential as a high-performance photoelectrode for sustainable solar hydrogen evolution. 

Abstract: The rapid and efficient detection of Escherichia coli O157:H7 (E. coli O157:H7) is important in preventing outbreaks due to water pollution and maintaining public health. Traditional diagnostic techniques tend to be time-consuming, require a lot of resources, and generate huge secondary pollutants. To prevent this, we report a low-cost, paper-based disposable electrochemical biosensor designed for sensitive detection of E. coli O157:H7. In this study, we have developed disposable paper electrodes (DPEs) using an indigenously synthesised carbon paste, optimised for improved adhesion and conductivity. A hybrid carbon nanocomposite of amine-functionalised carbon dots and multi-walled carbon nanotubes (CD/MWCNT) was synthesised via a single-step hydrothermal method and employed to modify the DPE surface to improve the signal transduction and antibody immobilization. The proposed biosensor displayed a low limit of detection of 0.7 CFU/mL with a sensitivity of 0.43 (ΔI/I)·(CFU/mL)/cm2 across a wide concentration range of 1.5 to 1.5 × 106 CFU/mL with acceptable specificity and no significant interference from other species of bacteria. Owing to the simple fabrication, strong analytical performance, and easy disposability, the designed DPE-based biosensor presents a promising platform for low-cost and point-of-care pathogen diagnosis. 

Abstract: Tailoring semiconductor properties through cation substitution is a promising strategy to improve the intrinsic properties of a photoabsorber material by improving charge carrier statistics, kinetics, and efficiency of photo-/electrocatalytic conversions. In the current study, Cu2ZnSnS4 (CZTS) thin film photocathodes are investigated by partially replacing Zn with Bi by fabricating Cu2Zn1−xBixSnS4 (x = 0.02, 0.04, 0.06, and 0.08) (x-CZBTS; x: 2, 4, 6, and 8) thin films. Incorporating Bi replacing Zn reduce bulk defects, secondary phases, and CuZn antisites and promote ease of crystallization with a decrease in crystallization temperature. Bi-doping modulates the CZTS film band-gap with a greater absorption coefficient, red shift, and charge collection. CZBTS coated with CdS/Pt (x-CZBTS-cp) films delivered photocurrent density (−4.0, −7.2, −5.2, and −1.3 mA cm−2 at 0 VRHE for x: 2, 4, 6, and 8, respectively). 4-CZBTS-cp with the highest J (ηSTH = 1.62% at 0.45 VRHE, 95 µmol cm−2 h−1 H2 evolution, F.E. = 90%, and Eonset = 0.71VRHE) showed 82% photocurrent density retention after 10h in 1 m kPi buffer (pH 7). DFT and experimental studies underscore improved PEC performance owing to significant Bi contribution in conduction band of CZBTS, lowering bandgap, elongating photogenerated charge carrier lifetime, rapid charge separation/transport, and charge accumulation at the Bi−S site on the surface with optimal Gibbs free energy (ΔGH*) for CZBTS on photoexcitation. 

Abstract: Water pollution from organic contaminants is one of the biggest problems affecting the globe today. Conventional wastewater treatment systems have been used many times to solve world water pollution problems. This study focuses on the development of Cu doped TiO2/g-C3N4 heterojunction nanocomposites to improve the effectiveness of visible light harvesting, increase charge separation and transfer efficiency, and enhance photocatalytic activity for the degradation of organic contaminants. The synthesized photocatalysts were extensively analysed using XRD, FTIR, BET, UV DRS, PL, SEM, TEM, and XPS methodologies. The superior photocatalyst (Cu-TiO2/g-C3N4) achieved the highest photocatalytic degradation efficiency for BPA, MB, CR, and EBT under visible light irradiation. The rate constant for photocatalytic degradation of BPA over the Cu-TiO2/g-C3N4 photocatalyst was 10.83, 8.86 and 3.48 fold greater than that of pure TiO2, pristine g-C3N4, and Cu-TiO2 photocatalysts, respectively. The rate constant decreased with the introduction of AO and TBA as they scavenge holes and hydroxyl radicals, respectively. The increased photocatalytic activity of the ternary photocatalyst is attributed to improved electron–hole pair separation and the creation of the type-II heterojunction structure. The photocatalytic parameters of BPA demonstrate that the Cu-TiO2/g-C3N4 photocatalyst could be used in real-world wastewater treatment applications. 

Abstract: Pathogenic E. coli O157:H7 remains a major global concern due to its role in foodborne illnesses, highlighting the need for more efficient detection methods. Conventional approaches to detect the bacteria samples are time-intensive and laborious. To address these issues, here we propose an impedimetric immunosensor for rapid and early detection of E. coli O157:H7 using an amino-functionalised graphite powder synthesised through a simple wet chemical functionalisation process. The synthesised amino-functionalised carbon was analytically characterized by various characterization techniques to confirm the surface functionalisation and its morphology. The developed biosensor demonstrated a theoretical detection limit (LOD) of 1.36 ± 0.16 CFU/mL across a concentration range of 1.5 CFU/mL to 1.5 х 106 CFU/mL. Notably, the biosensor exhibited an excellent selectivity to E. coli O157:H7 in the presence of interfering species and has a sensitivity of 4.43 ± 0.52 ((ΔΩ/Ω)/(CFU/mL))/cm². This developed sensor offers an effective pathway for the early diagnosis of E. coli to prevent foodborne outbreaks.

Abstract: Photocatalytic degradation effectively removes organic pollutants from wastewater, ensuring environmental safety. The current study successfully generated SrTiO3 NCs/PHI nanohybrids by a simple sonication method and used them for photocatalytic degradation of organic pollutants. The obtained samples were characterized by XRD, SEM, TEM, XPS, FT-IR, and UV-vis DRS. The results clearly indicated that SrTiO3 nanocubes are effectively spread within the layers of PHI. The catalysts were tested for photocatalytic degradation of crystal violet (CV), methylene blue (MB), rhodamine B (RhB), and Congo red (CR) under UV-visible irradiation. In comparison with other catalysts, SrTiO3 NCs/PHI exhibited exceptional decolorization of all four dyes, and pseudo-first-order kinetics were revealed. The nanocomposite activity exceeded those of SrTiO3 NCs and PHI in increasing charge carrier production, separation, and transport, as validated by PL, EIS, and photocurrent methods. The results of trapping tests showed that ˙OH, ˙O2−, and h+ species are crucial to the degradation process. The type-I heterojunction mechanism was suggested based on the results and Mott–Schottky plots, which were more consistent with the real conditions of the photocatalytic process. This research aims to establish a substantial strategy for enhancing the band structure of SrTiO3 with PHI to improve its photocatalytic efficacy.

Abstract: Solar energy conversion to chemical energy is a practical approach to sustainable development. Despite continuous advancements in energy technologies, conversion efficiencies remain shallow and below desired levels. Most research efforts are concentrated on absorbing the UV-Vis portion of solar radiation, with relatively little attention given to the infrared segment, even though it constitutes a substantial portion of solar radiation, accounting for ∼50 %. The photon energy in the NIR (Near-Infrared) range is insufficient. It does not correspond adequately to the semiconductor bandgap energy levels required to stimulate the generation of electrons and holes. However, novel nanomaterials are being scrutinized to absorb NIR light and generate photoexcited electrons/holes, which can be utilized to transform effectively through novel electron transfer pathways. Engineering surface and bulk properties of these NIR absorbing nanomaterials and harnessing NIR radiations have shown promising results in ameliorating the light conversion, yield, and faradaic efficiencies. This review article highlights the methodology, in-depth mechanistic models, current progress, and potential of NIR light in assisting organic dye degradation (waste water treatment), H2 production, CO2 reductions, N2 reduction through photocatalytic and photoelectrocatalytic pathways.

Abstract: Dry reforming of methane (DRM), a process that converts two major greenhouse gases, methane and carbon dioxide, into valuable syngas, presents a promising avenue for a more sustainable future. However, the reaction's high endothermicity and catalyst deactivation due to carbon formation poses significant challenges for its widespread adoption. To address these issues, this study investigated a series of promoted NiO/γ-Al2O3 catalysts, incorporating different promoters (Mg, Zn, and Mn). The catalysts were synthesized via solution combustion synthesis; the catalytic performance and carbon resistance of these catalysts were evaluated. Results demonstrated that manganese-promoted NiO/γ-Al2O3 exhibited superior performance, achieving methane and carbon dioxide conversions of 13.2% and 13.5%, respectively. Additionally, this catalyst exhibited higher total energy efficiency (3.3 mmol kJ⁻¹) and total specific energy input (2.7 J mL⁻¹) compared to its counterparts. The H2-to-CO ratio of approximately 1.1 at a discharge power of 1.5 W suggests its potential for direct application in the Fischer–Tropsch process, producing liquid fuels such as LPG, gasoline, diesel, and jet fuel. 

Abstract: A coaxial dielectric barrier discharge (DBD) as a non-thermal plasma reactor was utilized for the non-oxidative coupling of methane into higher hydrocarbons under ambient conditions. The DBD reactor was subsequently performed as a packed-bed dielectric barrier discharge using non-catalytic materials, including glass beads, glass wool, and glass capillary, which were introduced to investigate the non-catalytic reaction mechanism. Typical observation demonstrated that the dielectric glass materials packed with DBD might successfully activate the stable C–H bond to produce hydrogen and C2–C4 higher hydrocarbons without the application of any oxidants and additional thermal energy. Among the packing materials investigated, the DBD reactor packed with a glass capillary obtained a maximum CH4 conversion of 6.1%, with the energy efficiency reaching a maximum of 0.66 mmol kJ−1 at a discharge power of 1.38 W with an SEI of 4.14 J mL−1. The enhanced CH4 conversion was attributed to an alternation in the plasma discharge behavior with non-catalytic glass materials. Moreover, under these conditions, the low temperature of the discharge zone resulted in minimal solid carbon accumulation on the inner electrode surface of the plasma reactor.

Abstract: The formation of bacterial biofilms in chronic wounds worldwide significantly impedes the healing process. Silver nanoparticles (AgNPs) synthesized via an eco-friendly hydrothermal method using Chitosan and Ethylene Glycol (EG) have been developed and evaluated for their antibacterial and wound-healing capabilities to combat this challenge. The AgNPs, characterized by hydrodynamic diameters of 519 ± 7.21 nm (AgNO3 + Chitosan), 1041 ± 2.2 nm (AgNO3 + EG), and 752 ± 11.8 nm (AgNO3 + EG + Chitosan) via Dynamic Light Scattering, were tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Antibacterial efficacy was demonstrated through zone inhibition assays, with inhibition zones of up to 10–12 mm at 500 μg ml−1 for AgNO3 + EG + Chitosan, and MTT assays, showing cell viability reduced to <10% at 800–1000 μg ml−1 for both bacteria. The wound-healing potential was assessed using a scratch assay on L929 fibroblast cells, revealing a wound closure increase of approximately 70%–80% after 72 h with AgNO3 + EG + Chitosan compared to the control. Scanning Electron Microscopy, Ultraviolet-Visible Spectroscopy, and x-ray Diffraction were employed to confirm the nanoparticles’ morphology, optical properties, and crystallinity. The AgNPs derived from the Chitosan-EG combination exhibited the highest antibacterial and wound-healing efficacy, suggesting their substantial potential as a biocompatible solution for managing biofilm-associated chronic wounds. 

Abstract: Bacterial biofilms pose significant challenges to wound-healing, and to achieve successful wound-healing, it is imperative to develop strategies to prevent and eliminate these biofilms. This study aims to explore the potential of using Aloe vera extract for the green synthesis of silver nanoparticles (AgNPs) and to evaluate their antibacterial properties and effectiveness in wound-healing. AgNPs were synthesized hydrothermally, employing Aloe vera as a natural reducing and stabilizing agent. The antibacterial activity of these AgNPs was tested against Escherichia coli and Staphylococcus aureus using zone inhibition and MTT assays. The wound-healing capabilities were assessed through a scratch assay on fibroblast cells. Results indicated that the AgNPs exhibited significant antibacterial activity, increasing effectiveness with higher concentrations of Aloe vera used in synthesis. AgNPs were characterized via UV–VIS spectroscopy, SEM, and DLS, showing spherical shapes ranging from 255.5 ± 5.02 nm to 749.47 ± 24.12 nm, decreasing with increasing Aloe vera concentration. Biocompatibility assessments on L929 cells showed low cytotoxicity, with over 70% cell viability at 10 mg/mL. Wound-healing assays indicated faster closure due to enhanced cell migration and matrix deposition, likely due to the synergistic effects of AgNPs and Aloe vera's bioactive components. The findings of this study highlight the significant potential of these silver nanoparticles in wound-healing applications, owing to their potent antibacterial properties and ability to enhance the wound-healing process. 

Abstract: Water is an essential component for all life on earth, and the presence of antibiotics in water poses a potential threat to the environment. In this study, we report the synthesis of a CaFe2O4/CuWO4 composite photocatalyst that can be activated by visible light using a two-step process. This involved hydrothermal treatment followed by sol-gel combustion. The morphological structure, element composition, photoelectric response, and other properties of the synthesized catalyst were thoroughly examined using various techniques, including XRD, TEM, XPS, PL, and EIS. Tetracycline (TC) was selected as a test antibiotic to evaluate the photocatalytic efficiency of the composite catalyst. The CaFe2O4/CuWO4 composite exhibited 2.12 and 9.76-fold higher TC degradation efficiency compared to that of individual CaFe2O4 and CuWO4, respectively, during 210 min of visible light exposure. The matched band positions of CaFe2O4 and CuWO4 play a crucial role in enhancing photocatalytic activity by effectively separating and transferring light-induced carriers. O2-•, e-, and OH• were found to be the primary reactive species driving the process, and a plausible TC degradation mechanism was proposed. The composite catalyst demonstrated high stability and excellent recyclability. The findings have implications for understanding the mechanistic insights into visible light-enhanced photocatalysts for the degradation of water-borne organic pollutants. 

Abstract: Inexpensive Co metal-based catalysts are explored for catalytic hydrogenation reactions but their leaching, selectivity and stability issues have realistically debarred their usage. To combat this issue, this work presents stable and selective cobalt supported nitrogen-doped carbon catalysts prepared by using cellulose and melamine as sources for carbon and nitrogen, respectively and pyrolyzed at temperatures ranging from 500 to 800 °C under N2 atmosphere. The synthesized series of catalysts was examined for hydrogenation of furfural to furfuryl alcohol at 120 °C under 2 MPa of H2 pressure. All catalysts were characterized through different spectroscopic techniques to build their structural-activity relationship. Here, pyrolysis temperature has shown its supremacy in directing catalyst performance. The catalyst Co/NC-700 exhibited 83% furfural conversion with near 100% selectivity to furfuryl alcohol. The catalytic activity found depended on Co particle size and its crystallinity which was tuned by varying pyrolysis temperature. Pyrolysis temperatures influenced the interaction between N-doped carbon and Co metal, mesoporous structure N-doped carbon support, availability of Co nanoparticles and hydrogen spillover that contributed to the remarkable catalyst efficiency. The catalysts are easy to separate and reusable with consistent activity upon several cycles. Additionally, the extent of the Co/NC-700 catalyst was expanded to hydrogenation of various substituted aldehydes where it yielded decent to excellent yields of alcohols. 

Abstract: The exponential expansion of population and industry leads to the contamination of freshwater resources, and the actual effluent in real-world scenarios comprises many pollutants. Hence, it is necessary to research the simultaneous elimination of pollutants and find an appropriate adsorbent with economic viability. Here the tire pyrolyzed carbon (TPC) was chemically activated with KOH at 950 °C. Multiple physical and chemical characterization methods, including XRD, FTIR, BET, XPS, zeta-potential, and point of zero charge, were used to analyze the activated tire carbons. Tire-activated carbon with high surface 660 m2/g area synthesized is ATC 950 1:4. The batch experiments for individual and simultaneous adsorption were conducted with ATC 950 1:4. It has shown cent percent adsorption efficiency for both methylene blue (MB) and methyl orange (MO) during independent and simultaneous adsorption with 1 g/L adsorbent dosage and 30 ppm of pollutant. The adsorptions of MB and MO follow the Langmuir isotherm and pseudo-second-order. The thermodynamic parameters revealed that adsorption of these pollutants is spontaneous and endothermic. The adsorption mechanism involves H-bonding, π-π stacking interactions, and electrostatic interactions. By suitably tuning the surface chemistry of the adsorbent, it is possible to selectively remove the pollutant MB or MO. 

Abstract: Charge transfer pathways in heterojunctions are crucial for determining photoexcited charge generation, separation, and kinetics of surface reactions. Nature-inspired Z-scheme and type-I heterojunctions are most sought mechanisms in photo-assisted processes aimed at charge separation and achieving higher photovoltages, thereby improving photoconversion efficiencies. Herein, we present a novel strategy to control charge transfer pathway in p-n heterojunctions by modulating halide in a metal oxyhalide, combined with metal-organic framework (MOF)-templated CuO nanorods (M-CuO NRs). Charge transfer mechanisms and kinetics across p-n heterojunctions are systematically investigated using M-CuO NRs/BiOX (X = Cl, Br, and I) photocathodes for photoelectrochemical (PEC) hydrogen evolution reactions. Varying halide species led to transition in charge transfer mechanism, resulting in distinct PEC conversion characteristics. J = –5.6 mA cm⁻² at 0 VRHE and HC-STH (%) of 0.95% at 0.34 VRHE were achieved, while a J = –5.1 mA cm⁻² at 0 VRHE with HC-STH (%) of 0.85% at 0.40 VRHE was obtained for M-CuO NRs/BiOI and M-CuO NRs/BiOBr, respectively. Our findings demonstrate modulating halide in BiOX significantly impacts charge transfer pathways, enhancing PEC conversion kinetics and hydrogen evolution under solar irradiation. Comprehensive characterizations of M-CuO NRs/BiOX photoelectrodes were conducted, including crystalline structure, morphology, photoelectrochemical performance, and photophysical properties.

Abstract: Inexpensive Co metal-based catalysts are explored for catalytic hydrogenation reactions but their leaching, selectivity and stability issues have realistically debarred their usage. To combat this issue, this work presents stable and selective cobalt supported nitrogen-doped carbon catalysts prepared by using cellulose and melamine as sources for carbon and nitrogen, respectively and pyrolyzed at temperatures ranging from 500 to 800 °C under N2 atmosphere. The synthesized series of catalysts was examined for hydrogenation of furfural to furfuryl alcohol at 120 °C under 2 MPa of H2 pressure. All catalysts were characterized through different spectroscopic techniques to build their structural-activity relationship. Here, pyrolysis temperature has shown its supremacy in directing catalyst performance. The catalyst Co/NC-700 exhibited 83% furfural conversion with near 100% selectivity to furfuryl alcohol. The catalytic activity found depended on Co particle size and its crystallinity which was tuned by varying pyrolysis temperature. Pyrolysis temperatures influenced the interaction between N-doped carbon and Co metal, mesoporous structure N-doped carbon support, availability of Co nanoparticles and hydrogen spillover that contributed to the remarkable catalyst efficiency. The catalysts are easy to separate and reusable with consistent activity upon several cycles. Additionally, the extent of the Co/NC-700 catalyst was expanded to hydrogenation of various substituted aldehydes where it yielded decent to excellent yields of alcohols.

Abstract: In this work, we present structural, dielectric, optical and photocatalytic properties of room temperature phase of lead-free perovskite (Na0.5 Bi0.5)ZrO3 (NBZ) system. The structural and optical properties are analysed by combining first-principles density functional theoretical approach (DFT) and experimental characterizations. Conventional solid-state method is used for the synthesis process. X-ray powder diffraction and Rietveld refinement of the powder patterns at room temperature showed the NBZ material to be orthorhombic perovskite belonging to the space group Pnma. The calculated lattice constants of NBZ are found to be in good agreement with the experimental results. Dielectric study revealed the diffuse phase transition (DPT) in the vicinity of 290 °C. Based on the microscopic composition fluctuation model and phenomenological theory, a reasonable and effective characterizing parameter of the diffuseness degree of the DPT is defined. Band gap energy is estimated using UV–Vis spectroscopy and optical absorption spectrum. The photocatalytic performance evaluation is done by investigating the photo-degradation kinetics of different pollutants by NBZ under visible light irradiation. The highest degradation efficiency is achieved for Methylene Blue (MB) dye (99% within 180 min), followed by Rhodamine B (RhB), Methylene Blue (MB), and Congo Red (CR) and Methyl Orange (MO) dyes. Overall, our results suggest good efficiency for NBZ as photocatalytic agent with implications to large-scale photocatalytic applications for environmental and energy concerns. Furthermore, our study also provides several bench-mark important results on NBZ that have not been reported so far.

Abstract: The upcoming era of flexible and wearable electronics necessitates the development of low-cost, flexible, biocompatible substrates amenable to the fabrication of active devices such as electronic devices, sensors and transducers. While natural biopolymers such as Silk are robust and biocompatible, long-term flexibility is a concern due to the inherent brittle nature of soft Silk thin films. This work elucidates the preparation and characterization of Silk-polyurethane (Silk-PU) composite film that provides long-duration flexibility. More importantly, an electrochemical biosensing platform is developed by creating a three-electrode system using a screen printing technique. The solvents in the Ink had little impact on the film. As a proof of concept, the detection of E. coli, a highly infectious pathogen, was demonstrated using screen-printed electrodes (SPEs) modified with gold nanoparticles. This method effectively detected E. coli across a wide range of concentrations, with a detection limit of 0.12 CFU/mL. The entire surface functionalization and detection process did not impact the Silk-PU substrate. Even after rigorous bending tests, the results were consistent, demonstrating the robustness and flexibility of the Silk-PU film.

Abstract: The most practical application for wastewater treatment is the removal of dyes from aqueous solutions through fixed-bed column adsorption studies, which are conducted using MWCNT-foam. In this study, Multiwalled carbon nanotube (MWCNT)-foam nanocomposites were fabricated using the low-temperature chemical fusion (LTCF) process. These foam-based composites were subsequently employed in fixed-bed continuous flow column adsorption studies to remove anionic Congo Red (CR) and cationic Methylene Blue (MB) dyes from aqueous solutions. A fixed-bed column, packed with MWCNT-foam (bed height: 0.6 cm and 1.1 cm), was used to adsorb MB and CR from dye solutions (50 mg L-1). The column exhibited adsorption capacities of 5.6 mg g-1 and 7.8 mg g-1 for MB and CR, respectively, at a flow rate of 2 mL min-1. To assess the impact of bed height, flow rate, and initial dye concentration on column adsorption performance, breakthrough curves were analyzed using multiple models. The Thomas model provided the predicted adsorption capacities for both dyes as 14.46 mg g-1 for MB and 15.49 mg g-1 for CR. The 𝜏 values for both dyes were calculated using Yoon-Nelson model as 151 min for MB and 203 min for CR. The Adams -Bohart model predicted the N0 values as 17.33 mg L-1 for MB and 22.96 mg L-1 for CR. Moreover, the adsorption capacity of the MWCNT-foam composite in the fixed-bed column remained relatively stable even after three regeneration cycles, demonstrating its potential for long-term use in dye removal applications.

Abstract: A non-thermal plasma (NTP) system integrated with metal oxide (MOx, M= Co, Cu, Mn)-coated glass beads (GB) was developed to study the plasma-catalysed breakdown of isopropyl alcohol (IPA). The combined plasma-packed mode was a promising alternative to thermal catalysis, as it enhanced IPA degradation at atmospheric pressure and room temperature. When the discharge zone was filled with GB and MOx/GB, the plasma discharge properties improved, which can be attributed to the enhanced electric field produced by the glass beads. Additionally, the metal oxide layer serves as a catalytic base for the adsorption and desorption of IPA, and gas phase active species help IPA decomposition. Among the coated materials applied, MnOx/GB+ Plasma showed the highest IPA conversion (~70%) and maximum CO2 selectivity (~50%), while only plasma mode showed more CO selectivity. The role of acidic-basic sites and oxygen species has been discussed to better understand the products of plasma-catalytic IPA decomposition.

Abstract: Click chemistry has growing impact in drug discovery. It is an azide alkyne cyclo addition in presence of Cu(I) catalyst. Click reaction gives high yields with a variety of starting materials and easy to perform and insensitive to oxygen or water. However vast applications of Click reactions were studied with homogeneous catalyst. Main disadvantages of homogeneous catalysts are processing of the product and regeneration of the catalyst. These disadvantages can overcome by the use of heterogeneous catalysts. Thus heterogeneous catalysts are highly economic in industrial applications. This article reports the synthesis of highly stable and reusable heterogeneous nitrogen doped carbon encapsulated nano Cu2O (NCEN Cu2O) pom discs. These pom discs were synthesized under normal temperature and pressure conditions by using copper nitrate as precursor and triethanolamine as stabilizing agent, hydrazine hydrate as reducing agent. Water and propanol were used as solvents. Thus obtained reddish brown powder was washed with ethanol and filtered using membrane and analyzed using powder XRD, FT-IR, SEM, SEM–EDX, TEM, TEM-EDX, TEM-SAED, HR-TEM analyses. And it showed high activity and reproducibility towards Click chemistry in synthesis of 1,2,3 triazoles.

Abstract: Treatment of dye pollutants prior to their release into the environment remains a formidable challenge, persisting as a longstanding issue. This study focuses on the development of a multi-walled carbon nanotube foam (MWCNT-foam) through low-temperature chemical fusion (LTFC), resulting in a composite with a remarkably high accessible surface area (> 475 m2g-1). The MWCNT-foam exhibits a three-dimensional porous structure and demonstrates a notable affinity for organic dye adsorption. The efficacy of this composite was evaluated against various cationic dyes such as Methylene Blue (MB) and Crystal Violet (CV) as well as anionic dyes such as Congo Red (CR) and Eriochrome Black T (EB), and the composite showed removal rates exceeding 99% Furthermore, the study delved into the impact of initial dye concentration, adsorbent dosage, kinetics, and other factors on the performance of the MWCNT-foam composite. The adsorption process achieved equilibrium in 10 minutes and strongly correlated with the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacity of MWCNT-foam for MB, CV, CR, and EB was found to be 168.63 mg g−1, 147.49 mg g−1, 99.50 mg g−1, and 93.11 mg g−1, respectively. In order to showcase the potential of this material for continuous adsorption, a specialized cartridge was designed and employed to treat dye solutions, demonstrating the feasibility of continuous mode adsorption.

Abstract:  The occurrence of micropollutants and dyes in water sources has sparked alarm due to their significant impacts on aquatic ecosystems and human health. This study aims to utilize the tire pyrolyzed carbon (TPC) as a source of the adsorbent for removing Bisphenol A (BPA) and Methylene Blue (MB). The adsorbent was synthesized by chemical activation of TPC with KOH at 750 oC. The activated TPC was characterized for different physical and chemical characterization techniques such as XRD, FTIR, SEM, BET, XPS, and TPD and exhibits a higher adsorption capacity of 49.2 and 72.1 mg/g respectively for BPA and MB. The effect of initial concentration, dosage of adsorbent, and initial pH are evaluated for BPA and MB. The adsorption is mainly driven by hydrophobic, electrostatic, - interactions, and hydrogen bonding. The removal process follows the second order and Langmuir isotherms. The adsorbent shows excellent recyclability which makes it a potential source of removal of different water-borne pollutants. The production of activated carbon from tire waste is advocated for its economic and environmental benefits. 

Abstract: This paper focuses on the development and characterization of flexible, biocompatible substrates using Cellulose Acetate (CA), a natural biopolymer known for its biocompatibility and adjustable biodegradability. As proof of concept, electrochemical detection of Staphylococcus aureus was carried out using Au-nanoparticle modified Flexible Screen-Printed Electrode (FSPE) on the CA substrate. The key take away from the reliability studies is that the electrochemical performance is intact after multiple bending’s. Tensile strength of 2.75 +/-0.03 MPa is an indicative of the flexibility of the substrate. The substrate showed little degradation during the fabrication of SPE and the time-consuming surface functionalization protocols required for Au-nanoparticle deposition and bioreceptor immobilization. The selective and ultrasensitive detection of S. aureus (LOD: 0.13 CFU/mL) is a testimony for the robustness of the substrate in flexible electrochemical biosensor applications. 

Abstract:

Solar energy is a promising source for producing renewable hydrogen and harvesting the near infrared(NIR~52%) radiation. Herein, we synthesized CuxS nanodisks(NDs) with characteristic LSPR absorption in NIR, coupled with CuO NPs(Eg 1.6 eV) fabricating CuO/CuxS NDs photocathode for PEC water splitting. CuO/CuxS NDs delivered higher J, ABPE in alkaline (-10.3 mA cm-2, 3% at 0.34 VRHE) and neutral (-9.5 mA cm-2, 1.15% at 0.2 VRHE) conditions, surpassing CuO photocathodes by more than 3 and 3.3-times, respectively. Electrochemical studies suggested increased charge-carrier concentration, efficient charge-transfer, elongated lifetime of photogenerated electron owing to intimate contact between layers leading to internal electric field enhancement, charge separation. H2 production over CuO/CuxS photocathode was 80 µmol.cm-2.h-1, ηF=86%. DFT calculation underscores engineered CuO/CuxS substantially improves catalytic HER efficiency by tuning charge transfer, optimal ΔGH* at heterointerface. The study conveys principles applicable to various domains, facilitating the creation of vacancies in superior semiconducting materials for photo-electrocatalysts. 

Abstract:

Hydrogenated acrylonitrile butadiene rubber (HNBR) is a specialty elastomer exhibiting excellent mechanical properties apart from oil resistance. In the present study, fixed concentration of triallyl isocyanurate (TAIC) 3 parts per hundred (pphr)is used as a coagent along with different concentrations of dicumyl peroxide (DCP) at viz 1, 3 5, 7, 9, 11, and 13 pphr were used to crosslink the HNBR. The cure characteristics were obtained from the Moving Die Rheometer (MDR) and compared with heat of reaction(ΔH) data for each of the compositions. The cured sheets were subjected to mechanical properties using a universal testing machine (UTM). Present studies indicate that the crosslinking efficiency of HNBR will significantly increase in terms of rate of crosslinking by 2 times and the magnitude of crosslinking by 5 times with concentration of peroxide. In addition, mechanical properties are reduced beyond 3 phr of DCP in the presence of coagent, indicating additional crosslinking and a faster cure rate in HNBR than peroxide alone. The present paper describes the mechanism behind the observed trends. 

Abstract:

In the current combat warfare scenario where weapons keep evolving into more lethal forms capable of catastrophic destruction and annihilation, armor systems have become an indispensable counter-measure. Fabricating improved armor with light-weight and high-strength materials has thus become a matter of utmost importance. Polymer matrix composites reinforced with high-performance fibers are a great alternative to heavier metallic or ceramic laminates as they provide appreciable protection without any compromise on the agility and speed in a battlefield. Over the last decade or so, there has been extensive research on several grades of Glass/Epoxy and Aramid/Epoxy systems for use in personal protection and vehicle armor systems. Through this study, we aim to provide an alternative to conventional reinforcement with lighter, greener and more durable, basalt fibers. Epoxy matrix composite laminates prepared with E-Glass, Kevlar, Basalt and S-glass as reinforcement were compared for mechanical properties using a universal testing machine as well as for low-velocity impact performance via. instrumented drop-weight tester. Failure analysis of laminates post-impact were carried out through infra-red thermography followed by stereo-microscopy. Basalt reinforced laminates performed better than Kevlar and Glass reinforced laminates. The Basalt/Epoxy laminates were found to provide significant improvement in terms of energy absorption and damage tolerance. 

Abstract:

Photoelectrochemical (PEC) water splitting is an immensely effective method for producing hydrogen. In this study, we present the fabrication of an efficient photoanode based on a g-C3N4/Bi2S3/ZnS ternary heterojunction system using the doctor blade technique in combination with the SILAR (Successive Ionic Layer Adsorption Reactions) method. This ternary heterojunction demonstrates outstanding PEC performance, exhibiting a remarkable photocurrent density of 13.48 mA.cm-2 at 1.23 V vs. RHE under the alkaline medium. The enhanced photocurrent in the presence of hole scavengers could be due to sulfite oxidation. ZnS serves the dual purpose of preventing direct contact between Bi2S3 with the electrolyte (acting as a passivation layer) and offering an additional active energy state to enhance charge density lending operational stability to the photoanode. The Incident Photo to Current Efficiency (IPCE) of the g-C3N4/Bi2S3/ZnS photoanode is 2.98%, which is substantially greater than the 0.69% of the g-C3N4/Bi2S3 system. Furthermore, Electrochemical Impedance Spectroscopy (EIS) and Photoluminescence (PL) studies establishing efficient electron transfer at the heterojunction align well with the observed enhancement in photocurrent density of the fabricated electrodes.

Abstract:

The conversion of carbon dioxide (CO2) through non-thermal plasma catalysis has received significant attention as a promising approach to address both environmental and energy challenges. This review paper offers a comprehensive overview of recent advancements in CO2 conversion utilizing non-thermal plasma (NTP), focusing on its potential to achieve efficient and selective transformations of CO2 into valuable products, such as fuels and chemicals, at moderate reaction conditions. The unique ability of NTP to activate CO2 at ambient room temperature and atmospheric pressure offers a promising pathway to mitigate the greenhouse effect and reduce dependency on fossil fuels. We highlight the utilization of catalysts in combination with dielectric barrier discharge (DBD) plasma reactor, showcasing encouraging results in enhancing product selectivity and overall CO2 conversion. Nevertheless, challenges associated with the conversion of CO2 into specific oxygenates, like methanol, are also discussed. The maximum methanol selectivity reported from recent studies was ~86% from CO2 hydrogenation reaction with DBD reactor. This review provides valuable insights for researchers working on sustainable CO2 utilization strategies and aids in guiding future investigations in this burgeoning field.

Abstract:

Developing a superior heterostructured composite, optimizing performance through synergies from complementary advantages in diverse materials, remains an ongoing challenge. The rise in organic contaminants in freshwater bodies possesses a major threat to human health. Various dyes such as Rhodamine B, Eosin Y and Methylene Blue are found in excess concentration due to industrial usage and their removal is important for environmental remediation and contaminant-free water. In this study, we report synthesis and fabrication of Bi2MoO6/g-C3N4 (BM/CN) composite photocatalyst and Rhodamine B photodegradation studies. The composite photocatalysts have been characterized using XRD, TGA, FT-IR, UV–Vis, TRPL, SEM, TEM, XPS, electrochemical, and BET studies over g-C3N4, Bi2MoO6, and Bi2MoO6 (10–40 wt%) supported on g-C3N4 photocatalysts. The photocatalytic studies are performed using various composite photocatalysts of BM/CN show 30%-Bi2MoO6 supported on g-C3N4 (30BM/CN) exhibits maximum visible light activation for dye degradation with 3.6 and 2.4-fold higher rate of degradation than bare g-C3N4 and Bi2MoO6, respectively. Higher surface area, broad light absorption, enhanced lifetime, lower charge transfer and higher transient photocurrents of the composite photocatalysts compared to g-C3N4 and Bi2MoO6. Moreover, study is aided with scavenger tests to support the proposed mechanism.The increased photoactivity of 30BM/CN is due to the synergistic interplay of improved charge generation and a reduction in the electron-hole (e−/h+) recombination rate. 

Abstract:

The utilization of the dielectric barrier discharge (DBD) plasma process presents a promising avenue for transforming carbon dioxide (CO2) into valuable compounds. In this research, we explore the integration of DBD plasma with a NiOx/γ-Al2O3 catalyst to amplify the efficiency and selectivity of CO2 conversion into carbon monoxide (CO). A series of NiOx-loaded on γ-Al2O3 catalysts were synthesized through wet impregnation and employed in the DBD plasma reactor. The synergy between non-thermal plasma and NiOx/γ-Al2O3 resulted in a significant enhancement in CO2 conversion, particularly demonstrating a notable increase in the energy content of produced carbon monoxide (CO). Enhanced conversion rates and selectivity were observed. Notably, the NiOx/γ-Al2O3 catalyst with a 15wt% loading exhibited the highest CO2 conversion of approximately ~ 9% at an applied voltage of 22 kV, accompanied by an energy efficiency of 1.13 mmol kJ-1. This study provides a comprehensive analysis of the impact of plasma-catalyst coupling on CO2 conversion into CO, showcasing the potential of hybrid DBD reactor systems for large-scale CO2 conversion and contributing to sustainable and value-added fuels production. The superior performance of the hybridized system is attributed to enhanced charge deposition and modified gas-phase chemistry resulting from the integration of the catalyst. Furthermore, we employed BOLSIG + software to calculate the mean electron energy and electron energy distribution function for different packing conditions, enhancing our understanding of the system's behavior and contributing valuable insights to the overall study.

Abstract:

The rational design of nitrite sensors has attracted significant research interest due to their widespread use and the associated risks of methemoglobinemia and carcinogenicity. The undisclosed nitrite sensing performance of the spinel cobaltite MnCo2O4 (MCO) prepared by an oxalate-assisted coprecipitation method has been reported in this study. Spectroscopy and microscopy investigations revealed the formation of uniform MCO nanorods with a high aspect ratio. The electrocatalytic nitrite oxidation at MCO-coated GCE (MCO/GCE) indicated the promising performance of the synthesized material for nitrite sensing. MCO/GCE detects nitrite in a concentration range of 5 µM to 3 mM and has an LOD of 0.95 µM with a higher sensitivity of 857 μA mM−1 cm−2 in a response time of 4 s. In MCO, the mixed-valence states of Co2+/Co3+ confer a high electrical conductivity and higher valent redox couples of Mn and Co impart remarkable electrocatalytic activity towards nitrite oxidation. MCO spinel undergoes facile and ultrafast faradaic reactions to mediate nitrite oxidation. Additionally, the mesopores of MCO nanorods facilitate the rapid diffusion of electrolyte and nitrite ions. Employing the electrode in sensing nitrite in milk, lake, and tap water samples further validates its potential application in real-life testing. MCO spinel nanorods showcase promising scope for utilization in the electrochemical sensing of nitrite and inspire further exploration of transition metal oxide-based mixed spinel materials. 

Abstract:

This study describes the synthesis of amino-functionalized carbon nanoparticles derived from biopolymer chitosan using green synthesis and its application towards ultrasensitive electrochemical immunosensor of highly virulent Escherichia coli O157:H7 (E. coli O157:H7). The inherent advantage of high surface-to-volume ratio and enhanced rate transfer kinetics of nanoparticles is leveraged to push the limit of detection, without compromising on the selectivity. The prepared carbon nanoparticles were systematically characterized by employing CO2 -Thermal programmed desorption (CO 2 -TPD), Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-visible), and transmission electron microscopy (TEM). The estimated limit of detection of 0.74 CFU/mL and a sensitivity of 5.7 ((ΔR ct /R ct )/(CFU/mL))/cm 2 in the electrochemical impedance spectroscopy (EIS) affirms the utility of the sensor. The proposed biosensor displayed remarkable selectivity against interfering species, making it well-suited for real-time applications. Moreover, the chitosan-derived semiconducting amino-functionalized carbon shows excellent sensitivity in a comparative analysis compared to highly conducting amine-functionalized carbon synthesized via chemical modification, demonstrating its vast potential as an E. coli sensor.

Abstract: 

Sustainable energy harvesting has emerged as a frontier research area and relentless efforts are being put in to tackle the tenacious issues of global warming and energy crisis. Photoelectrochemical (PEC) water splitting is regarded as a promising technology to produce H2. In this study, we report facile fabrication of ZnS modified SrTiO3/Bi2S3 (STO) heterojunction photoanode for PEC water splitting. Ternary heterojunction photoanode was fabricated using sol-gel followed by SILAR methods. Coupling of wide band gap STO with narrow band gap Bi2S3 photosensitizer extends the absorption edge while the ZnS passivation layer improves electrode stability by preventing direct contact of Bi2S3 with electrolyte and providing an active energy state for facile charge transfer to improve charge separation. Decreased rate of recombination and elongated lifetime of photogenerated charge carriers resulted in enhanced charge carrier dynamics. STO/Bi2S3/ZnS photoanodes displayed a photocurrent density (J) of 1.89 mA.cm-2 at 1.23 V vs RHE and HC-STH of 1.19% at 0.42 V vs RHE in neutral medium while the corresponding values in basic medium were J = 5.08 mA cm-2 at 1.23 V RHE and HC-STH 4.8% at 0.71 V vs RHE; considerably higher than bare STO and binary STO/Bi2S3 electrodes. The superior performance in basic medium could be attributed to the presence of hole scavengers. The improved photostability >3000 s was attributed to ZnS deposition. To better under the role of hole scavengers the quantification of O2 and H2 was undertaken. 

Abstract: 

Fairy chemicals (FCs), such as 2-azahypoxanthine (AHX), are a potential new class of plant hormones that are naturally present in plants and produced via a novel purine metabolic pathway. FCs support plant resilience against various stresses and regulate plant growth. In this study, we developed a four-step method for synthesising AHX from 2-cyanoacetamide, achieving a good yield. Oxime was obtained from 2-cyanoacetamide via the oximation reaction. Cascade-type one-pot selective Pt/C-catalysed reduction of oxime, followed by a coupling reaction with formamidine acetate, yielded intermediate 5-amino-1H-imidazole-4-carboxamide (AICA). For the synthesis of AICA from oxime, we used modern fine bubble technology, affording AICA in 69% yield. Subsequently, we synthesised 4-diazo-4H-imidazole-5-carboxamide (DICA) from AICA via the diazotisation reaction. Notably, the synthesis of DICA from AICA was achieved, and the stability of previously known less stable DICA in the solid state was confirmed. Finally, PhI(OAc)2 (0.5 mol%) catalysed the intramolecular cyclisation of DICA in the green solvent water to yield AHX (overall yield of 47%). This study's innovative techniques and substantial discoveries highlight its potential influence and significance in FCs science, thereby establishing a new standard for subsequent research.

Abstract

E-Glass/epoxy prepregs are undisputedly a great advancement in processing and fabrication technology. They offer immense advantages over conventional composite manufacturing processes in terms of waste reduction and efficient manufacturing times. These prepregs are used in several industries including but not limited to automobile, construction, defence and aerospace. Their versatility and wide applicability however is shadowed by intricate storage and handling requirements. Prepregs usually need to be stored at below freezing temperatures and hence lose their chemical integrity during transportation if not handled properly leading to a lot of wastage and scrap generation. Therefore, it is essential to develop a rigorous regime in order to determine the shelf-life and usability of these prepregs. Hereby, we report an extensive experimental design for assessing shelf-life of commercially available prepregs using techniques like DSC and IR and corelating the findings with mechanical data. The degree of pre-cure increased to 30% as a result of exposure to moisture over prolonged time and a substantial decrease in mechanical strength was observed. The shelf-life was found to be about 7 weeks and a strong agreement between analytical and mechanical data was observed.

Abstract

The present work studied the decomposition of isopropyl alcohol (IPA), widely used in chemical industries and households, in a packed-bed dielectric barrier discharge (DBD) plasma reactor. Metal oxide (MOx) coated on γ-Al2O3 (M = Cu, Mn, Co) was utilized for packing. The plasma-packed mode was a likely alternative to the conventional removal techniques, as it aids the conversion of dilute concentrations of IPA to CO and CO2 at ambient conditions (room temperature and atmospheric pressure). The mean electron energy calculations suggest that electrons with higher energy are generated when the discharge zone is packed with catalysts. When comparing IPA conversion (input concentration of 25 ppm) for no packing mode and MOx/γ-Al2O3 coupled plasma mode, the latter method enhances conversion to greater than 90% at an applied voltage of 18 kV. Also, MOx/γ-Al2O3 showed the highest selectivity to CO2 (70%) compared to plasma-only mode (45%). The metal-oxide layer provides the necessary catalytic surface facilitating the oxidation of IPA to COx through active oxygen species or the interaction of surface hydroxyl groups. The use of MOx/γ-Al2O3 resulted in about 90% carbon balance and reduced ozone generation, demonstrating the significance of integrating metal oxide to achieve efficient conversion and maximal selectivity towards the desired products. 

Abstract

The requirement of green, sustainable, and prudent chemical procedures is one of the bottlenecks in synthetic organic chemistry. Nanostructured materials have the promise to fill the gap between homogeneous and heterogeneous catalysis and can offer benefits without compromising the selectivity in forming the desired products. Advancement of sustainable and green chemical processes under environmental benign conditions is one of the immense interests in modern organic chemistry. Significantly, the hydrogenation of nitroarenes is one of the most important useful catalytic processes in the fine and bulk chemical industry. The most recent advancement of catalysts with supported metal nanoparticles has prompted their enormous accomplishments in the course of the most recent years, provoking their noteworthy applications as “standard” catalysts. Currently, this topic has gotten a lot of consideration. However, despite the fact that support materials have a great diversity in the catalysts for the reactions and modifications, a systematic rationalization of the field is lacking. In this review, we cover and categorize the recent progress in support materials tuning strategies to enhance catalytic performance for the hydrogenation of nitroarenes. Also, importance of support materials in the heterogeneous catalytic hydrogenation of nitroarenes is discussed. 

Abstract

Removal of Arsenic, a potent carcinogen from aqueous environments is imperative to ensure the provision of potable water and to mitigate the risks associated with its exposure. In this study, we explore a composite based on biochar derived from coconut-shell loaded with Cerium Oxide for the removal of Arsenic (As(V)) by adsorption. The synthesized adsorbent combines the characteristic high specific surface area of carbon materials with high adsorption affinity of CeO2 towards Arsenic to create a synergistic effect. Various parameters such as initial concentration, adsorbent dosage, presence of coexisting anions etc., were investigated to determine the kinetics and thermodynamics of adsorption. The effect of initial pH on the adsorption was also investigated and maximum removal efficiency of around 99 % was observed. A very high adsorption capacity was observed and highlighting the genesis of a highly effective adsorbent for the removal of As(V) incorporating an inexpensive and ecologically acceptable approach. 

Abstract

Zero-dimensional hybrid copper(I) halides (HCHs) are attractive due to their interesting photoluminescence (PL) properties and the high abundance and low toxicity of copper. In this study, we report green–red dual emission from rhombic 1-butyl-1-methyl piperidinium copper bromide [(Bmpip)2Cu2Br4] microcrystals (MCs) prepared on borosilicate glass. The structure and elemental composition of the MCs are characterized by single crystal X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Interestingly, MCs prepared on an ITO-coated glass plate show an intense green emission compared to the dual emission on a bare glass or plastic substrate. Furthermore, the intensity of the green emission from the MC is enormously increased by powdering using a conductive material, suggesting the deactivation of the red-emitting state by a charge transfer interaction with the conductor. These findings open a new strategy to suppress the self-trapping of excitons by longitudinal optical phonons and control the dual emitting states in HCHs. 

Abstract

Ground granulated blast furnace slag (GGBS) is a primary industrial waste product of iron production, and its improper disposal has been a serious environmental problem. This study aims to modify the GGBS using oxalic acid (GGBS-Ox) for the adsorption of tetracycline (TC) from an aqueous solution. GGBS-Ox was synthesized and characterized via FTIR, XRD SEM, XPS, BET, and DLS. The effects of process parameters, involving initial solution pH, stirring speed, and contact time, are evaluated by utilizing response surface methodology (RSM), artificial neural network (ANN), and random forest (RF) based models. The experimental results indicate that the removal efficiency of TC is significantly affected by the initial pH of the solution. The RSM, ANN, and RF models accurately simulated the experimental data, as indicated by the high coefficient of determination (R2), which was 0.98, 0.95, and 0.98, respectively. Additionally, kinetics, isotherm, and thermodynamic models were evaluated for the adsorption of TC onto GGBS-Ox. The findings of this study demonstrated the utilization of GGBS-Ox as an efficient and sustainable adsorbent for the treatment of TC and can be considered as a potential adsorbent for wastewater treatment. 

Abstract

Emerging contaminants in wastewater are one of the growing concerns because of their adverse effects on human health and ecosystems. Adsorption technology offers superior performance due to its cost-effectiveness, stability, recyclability, and reliability in maintaining environmental and health standards for toxic pollutants. Despite extensive research on the use of traditional adsorbents to remove emerging contaminants, their expensiveness, lack of selectivity, and complexity of regeneration remain some of the challenges. Industrial wastes viz. blast furnace slag, red mud, and copper slag can be used to develop efficacious adsorbents for the treatment of emerging contaminants in water. Advantages of the use of such industrial wastes include resource utilization, availability, cost-effectiveness, and waste management. Nevertheless, little is known so far about their application, removal efficacy, adsorption mechanisms, and limitations in the treatment of emerging contaminants. A holistic understanding of the application of such unique industrial waste-derived adsorbents in removing emerging contaminants from water is need of the hour to transform this technology from bench-scale to pilot and large-scale applications. This review investigates different water treatment techniques associated with industrial waste-based adsorbents derived from blast furnace slag, red mud, and copper slag. Besides, this review provides important insights into the growing trends of utilizing such novel types of adsorbents to remove emerging contaminants from water with an emphasis on removal efficacy, controlling measures, adsorption mechanisms, advantages, and limitations. The present timely review brings the current state of knowledge into a single reference which could be a strong platform for future research in understanding the latest advancements, decision making, and financial management related to the treatment of wastewater using industrial waste-based adsorbents.

Abstract

Photoelectrochemical water splitting has been envisaged as a promising green technology for efficient solar-to-fuel conversion. Graphitic carbon nitride (g-C3N4 ) demands prime focus amongst the emerging class of potential 2D materials for energy harvesting and storage on account of its high chemical/thermal stability and metal-free nature. The unique characteristics of the material enables its application both as a photocathode or photoanode. However, the low photocurrent density of pristine g-C3N4 curbs its possible commercial application. Considerable attempts to modify the electrodes via nano-structuring, heteroatom doping, heterojunction formation, etc. are in progress. The current review offers insight into the potential and limitations of g-C3N4 as a photoanodic/cathodic material.

Abstract

Developing an efficient photocathode system from earth abundant materials is essential for effectual Photoelectrochemical (PEC) water splitting. Charge transfer between heterojunctions is important in fabricating a novel photocathode, keeping cost-effectiveness, abundance, and PEC performance in mind. The p-type narrow band gap photocathode, CuO (Eg = 1.5 eV) synthesized by hydrothermal method, was decorated with Sb2S3 Nanospheres (NSs) by adopting a facile chemical bath deposition (CBD) procedure to fabricate CuO/Sb2S3 NSs heterojunction. Fabricated heterojunction showed better PEC performance contrary to bare CuO, improvement in photocurrent density CuO/Sb2S3 NSs (J = -1 mA.cm-2) than CuO (J = -0.3 mA.cm-2) photoelectrode at 0 VRHE  in 0.5 M Na2SO4 (pH 6.85) is due to enhanced charge carrier generation/separation. The photostability of CuO/Sb2S3 remains intact for 2.5 h with no degradation in photocurrent density. Sb2S3 works as a sensitizer, diminishing the recombination rate of the e-/h+ in CuO/Sb2S3 NSs. UV-Visible and photoluminescence(PL) emission spectra results suggested CuO/Sb2S3 enhanced absorption spectrum and reduced rate of recombination. Electrochemical impedance spectroscopy studies show less charge transfer resistance for CuO/Sb2S3 NSs than CuO. This finding will pave new path in developing novel photocathodic material configurations and heterojunction with Cu-based binary oxides/chalcogenides for solar harvesting. 

Abstract

Detecting gram -ve bacterial colonies is crucial in addressing the clinical challenges associated with chronic wounds and delayed healing. These bacteria can exacerbate wound conditions, hindering natural healing and potentially leading to infections. The electrochemical sensing platform presented in this study serves as a valuable tool for healthcare professionals to make timely and targeted treatment decisions. Towards this, we developed a cost-effective electrochemical sensing platform leveraging the TLR4/MD-2 complex to detect gram -ve bacterial colonies. Our biosensors were meticulously fashioned using Polyaniline (PANi) and Hollow-Polyaniline (HPANi) nanofibers. Notably, the HPANi-based sensors, owing to their distinctive hollow structure, facilitated amplified responses under comparable experimental conditions compared to PANi-based counterparts. The designed sensing platform demonstrated exceptional accuracy in identifying Escherichia coli (gram -ve), showcasing a theoretical detection limit of 0.215 CFU/mL for PANi and a remarkably improved 0.14 CFU/mL for HPANi. These sensors displayed outstanding selectivity for gram -ve bacteria, even amidst gram +ve bacteria and fungi. Moreover, our platform demonstrated remarkable sensitivity, yielding 3.04 ((ΔR/R)/CFU/mL)/cm² for the HPANi-based sensor, surpassing the performance of the PANi-based sensor at 1.98 ((ΔR/R)/CFU/mL)/cm². 

Abstract

Bacterial biofilms in chronic wounds are primarily responsible for delayed wound healing and affect a person’s life quality. A patient’s recovery depends on the treatment based on the speedy diagnosis of the wound or bacteria responsible for biofilm formation. Identification plays an essential role in the best recovery of a patient, and electrochemical techniques are best suited. In this work, we utilized the cost-effective and in-house developed carboxylic-terminated carbon paste electrode’s surface immobilized with TLR-4 to identify gram-ve bacteria, i.e., E.coli. A miniaturized electrochemical cell was used to accommodate these electrodes, which also helped in reducing sample wastage and improving the detection limit. The fabricated electrodes detected E.coli with a very low detection limit of 0.13 CFU/mL. When tested with nonspecific bacteria and fungi, the proposed platform demonstrated excellent specificity and selectivity towards gram -ve bacteria and the mixture of both gram +ve/-ve bacteria and fungi. The bioelectrodes stored for more than two weeks were tested on various days, and the results indicated an excellent shelf-life for the proposed platform. 

Abstract

The comprehensive study on the impact of different synthesis techniques on the structural, electrical, and photocatalytic properties of perovskite ferroelectric ceramics K0.5Na0.5NbO3 (KNN). The solid-state reaction and hydrothermal methods are used to prepare the KNN ceramics, and the effects of grain size on the physical characteristics these ceramics are examined. The KNN-S prepared by solid-state method have significantly larger grain size as compared to that for KNN-H prepared by hydrothermal method. Furthermore, the KNN-S is found to exhibit higher dielectric, piezoelectric and ferroelectric properties as compared to KNN-H. On the other hand, the increased photocatalytic activity is observed in KNN-H as compared to KNN-S. As compared to the hydrothermal synthesis, the solid-state synthesis causes an increase in the relative dielectric permittivity from 2394 to 3286, remnant polarization from 15.38 to 20.41 μ μC/cm2, planer electromechanical coupling factor from 0.19 to 0.28 and piezoelectric coefficient  from 88 to 125 pC/N. The KNN-S ceramics are also found to have a lower leakage current density, and higher grain resistance than KNN-H ceramic. The enhanced photocatalytic activity of KNN-H is attributed to relatively smaller particle sizes. The KNN-S and KNN-H samples are found to have degradation efficiencies of RhB solution of 20% and 65%, respectively. The study highlights the importance of synthesis methods and how these can be exploited to tailor the dielectric, piezoelectric and photocatalytic properties of KNN. 

Abstract

Engineering low-cost and efficient materials for sensing Hydrazine (HA) is critical given the adverse effects of high concentrations on humans. We report an efficient electrode made up of rod-shaped Co3O4/g-C3N4 (Co3O4/GCN) coated fluorine doped tin oxide as a desirable electrode for the detection of HA. GCN is synthesized by thermal decomposition of melamine, Co3O4, and the heterostructure is grown by a hydrothermal process. The as-prepared materials were characterized by using spectroscopic and microscopic techniques. The voltammetric studies showed that HA can be oxidized at a lower onset potential of 0.24 V vs. reference Ag/AgCl, and the composite yielded a significantly enhanced oxidation peak current than the pure components because of the high electrocatalytic activity and the synergy between Co3O4 and GCN. By employing chronoamperometry, the proposed sensor can detect HA in a wide range with a high sensitivity of 819.52 µAmM-1cm-2 and a detection limit of 3.14 µM. The high conductivity of Co3O4, enhanced electroactive surface area, the rich redox couples of Co2+/Co3+, and the additional catalytic sites from GCN are responsible for the high performance of the heterostructure. 

Abstract

The rise in demand for biomass as a renewable energy source is being seen as an alternative energy source to conventional fossil fuels. Blending of biodiesels and bioethanol in gasoline is the initial step towards complete utilization of biomass fuels. Glycerol is a byproduct generated in vast quantities during biodiesel production. Glycerol on further oxidation can produce several value-added products in conjunction with hydrogen (H2) through photo-/electrocatalysis (PEC/EC). The valuable products from glycerol include 1,3-dihydroxyacetone, glyceraldehyde, tartronic acid, formic acid, and glyceric acid. Glycerol can be used as a feedstock in PEC/EC cells along with water. An intriguing strategy unfolds by combining the oxidation of biomass-derived compounds at the anode with the hydrogen evolution reaction taking place at the cathode, all contained within a biomass electrolysis or photo-reforming reactor. This approach allows for the simultaneous production of high-value chemicals and hydrogen, while minimizing energy consumption and reducing CO2 emissions. This review seeks to integrate essential insights into photo and electro-assisted catalysis, with the objective of offering a holistic comprehension of the overall reaction mechanisms involved in the photo-/electrocatalytic oxidation of glycerol. At the same instance, various transition metal-based photo-/electrocatalysts for glycerol valorization are reviewed and discussed in great details. Moreover, this evaluation carefully examines the potential regarding the obstacles and possibilities in the advancement of photo-/electrocatalytic glycerol oxidation, aligning with the future demands for sustainability in the global energy landscape. 

Abstract

In this report, CuBi2O4 and CuBi2O4/MnO2 are synthesized using coprecipitation and hydrothermal methods respectively. CuBi2O4/MnO2 has been extensively used for the electrochemical detection of hydroxylamine. CuBi2O4 and CuBi2O4/MnO2 are well characterized by XRD, XPS, FESEM to reveal the structural and morphological features of the material. Electrochemical measurements like CV, chronoamperometry, impedance is studied to reveal the electrochemical behavior of CuBi2O4/MnO2 towards hydroxylamine. Stability, reproducibility and interference studies are performed to reveal the suitability of CuBi2O4/MnO2 as an electrode material for electrochemical detection of hydroxylamine.

Abstract

Chronic wounds caused due to bacterial biofilms are detrimental to a patient, and an immediate diagnosis of these bacteria can aid in an effective treatment, which is still an unmet clinical need. An instant and accurate identification of bacterial type could be made by utilizing the Toll-Like Receptors (TLRs) combined with Myeloid Differentiation factor 2 (MD-2). Given this, we have developed an electrochemical sensing platform to identify the gram-negative (gram-ve) bacteria using TLR4/MD-2 complex. The nonthermal plasma (NTP) technique was utilized to functionalize amine groups onto the carbon surface to fabricate cost-effective carbon paste working electrodes (CPEs). The proposed electrochemical sensor platform with a specially engineered electrochemical cell (E-Cell) identified the Escherichia coli (E. coli) in a wide linear range of 1.5×10° - 1.5×106 C.F.U./mL, accounting for a very low detection limit of 0.087 C.F.U./mL. The novel and cost-effective sensor platform identified gram-ve bacteria predominantly in a mixture of gram positive (gram+ve) bacteria and fungi. Further, towards real-time detection of bacteria and point-of-care (PoC) applications, the effect of the pond water matrix was studied, which was minimal, and the sensor could identify E. coli concentrations selectively, showing the potential application of the proposed platform towards real-time bacterial detection. 

Abstract

We employed a solvothermal and thermal pyrolysis approach to prepare a heterojunction of oxide perovskite (Bi2MoO6) dispersed on polymeric carbon nitride (PCN) sheets. The introduction of Bi2MoO6 particles onto PCN sheets improved the light absorption characteristics of the Bi2MoO6/PCN heterojunction. As synthesized Bi2MoO6/PCN heterojunction exhibited a larger surface area of 24.5 m2/g, compared to the individual Bi2MoO6 (18.2 m2/g) and PCN (7.3 m2/g), respectively. This enhanced surface area provided newer catalytic sites for the heterojunction. The resulting heterojunction was employed as a photocatalyst for the reduction of a series of toxic mono, di, and tri-nitrophenols, namely 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 2,4,6-trinitrophenol, into industrially important amino phenols. By utilizing visible light irradiation and NaBH4 as a reducing agent, the Bi2MoO6/PCN photocatalyst demonstrated accelerated reduction kinetics than individual catalysts. This enhanced performance was attributed to the larger surface area and suppressed charge carrier recombination of Bi2MoO6/PCN heterojunction, which facilitated efficient photoreduction. Overall, this study sheds light on the promising application of oxide perovskite/PCN heterojunction systems in photocatalytic reduction reactions, offering a viable solution for mitigating emerging pollutants. 

Abstract

Hydrogen has tremendous potential as a sustainable energy source for the future. Unassisted photoelectrochemical water splitting is a promising approach to producing hydrogen fuel from sunlight and water. To economically produce hydrogen, efficient, low-cost, environmentally friendly, and long-term stable photocathodes and photoanodes are needed. In this study, we have fabricated CuBi2O4 (CBO) photocathodes using drop-casting, hydrothermal, and electrodeposition methods. The resulting photocathodes have nanoparticle, nanosphere, and flake-like structures. The drop-casted CBO (D-CBO) exhibits an impressive onset potential of 0.9 V with a photocurrent density of −3.0 mA·cm–2 at 0 V vs reversible hydrogen electrode (RHE) and a solar to hydrogen (STH) efficiency of 0.61% at 0.23 V vs RHE, which is higher than hydrothermal CBO (H-CBO) and electrodeposited CBO (E-CBO). The high onset potential of the D-CBO photocathode results in a good unbiased operating photocurrent of −1.8 mA·cm–2, which is assisted by the BiVO4 (BVO) photoanode. The BVO photoanode has a photocurrent density of 1.6 mA·cm–2 at 1.23 V vs RHE. This study demonstrates hydrogen production from a BVO-CBO tandem cell and highlights the importance of photovoltage in tandem devices for overall water splitting, particularly in devices with CBO photocathodes 

Abstract

Hydrogen is gaining significant attention as a clean fuel option due to its high energy density, which can be produced through solar water splitting. In this study, S-TiO2 photocatalyst has been synthesized using the sol-gel method. Analysis revealed that cation substitution S+4 and S+6 of Ti+4 in the TiO2 lattice resulted in the formation of S=O bond and S-Ti-O bond. The S-TiO2 was then coated with BiSbS3 using the chemical bath deposition (CBD) method, followed by the deposition of FeOOH using the similar technique. The resulting photoelectrode, S-TiO2/BiSbS3/FeOOH, exhibited a photocurrent density of 4.36 mA.cm−2 at 1.23 V vs reverse hydrogen electrode and a solar-to-hydrogen efficiency of 1.31% at 0.6 V vs RHE, outperforming other electrodes. The improved photoactivity was attributed to the synergetic effect of heterojunction and cocatalyst loading. This study provides insight into the potential applications of cocatalysts in (photoelectrochemical) PEC water splitting.

Abstract

Climate change and its detrimental effects on the environment have led to an urgent need for a transition toward a fossil-free energy future. To achieve this goal, renewable energy sources, especially hydrogen, will play a crucial role. However, to make them more viable, various sectors like Power, Industrial, Mobility, etc., are looking for ways to store and transport the energy generated from hydrogen. The advancement of Power-to-X (PtX) technologies has caught attention, as it offers a solution for converting renewable energy into chemical or fuel forms that can be used in various applications and overcome the problem of storage associated with hydrogen. This concept is being looked at as a potential game-changer in the energy sector. This review focuses on two key areas within the Power-to-X (PtX) technology that holds significant potential for transitioning towards a fossil-free energy future: eFuels synthesis and Direct Air Capture (DAC) technology. efuels provide an opportunity for nations to increase energy independency or reduce greenhouse gas emissions by supplying energy-dense fuels which are miscible with conventional fossil fuels. DAC technology, on the other hand, captures Carbon dioxide (CO2) from the air and converts it into efuels. By reducing the amount of CO2 in the atmosphere, DAC technology can help to slow the effects of climate change. Overall, both eFuels synthesis and DAC technology have the potential to play a vital role in the transition toward a fossil-free energy future. They offer solutions to both stationary and mobile applications while also making a substantial reduction in greenhouse gas emissions, thereby helping to alleviate the impacts of climate change. In this paper, we intend to provide a summary on efuels synthesis, DAC, and their impact on the existing energy equipment. 

Abstract

Transition metal-catalyzed tandem reactions are highly prominent in organic synthesis. Especially, palladium-catalyzed biscarbofuctionalization of alkenes is remarkable. However, enabling this type of tandem reaction through heterogeneous catalysis is the most desirable. In this context, silica-supported Pd nanoparticles catalyzed tandem Heck followed by Suzuki coupling reaction has been developed via a dual C–C bond formation. The significance of silica support has also been examined. Excellent catalytic performance was shown by the designed catalyst and enabled the construction of dihydrobenzofurans and oxindoles in good to excellent yields and with good functional group tolerance. Despite being recycled numerous times, the catalyst maintained its catalytic efficiency. 

Abstract

Halide vacancies cause lattice degradation and nonradiative losses in halide perovskites. In this study, we strategically fill bromide vacancies in CsPbBr3 perovskite nanocrystals with NaBr, KBr, or CsBr at the organic–aqueous interface for hydrophobic ligand-capped nanocrystals or in a polar solvent (2-propanol) for amphiphilic ligand-capped nanocrystals. Energy-dispersive X-ray spectra, powder X-ray diffraction data, and scanning transmission electron microscopy images help us confirm vacancy filling and the structures of samples. The bromide salts increase the photoluminescence quantum yield (98 ± 2%) of CsPbBr3 by decreasing the nonradiative decay rate. Single-particle studies show the quantum yield increase originates from the poorly luminescent nanocrystals becoming highly luminescent after filling vacancies. Furthermore, we tune the optical band gap (ultraviolet–visible–near-infrared) of the hydrophobic ligand-capped nanocrystals by halide exchange at the toluene–water interface using saturated NaCl or NaI solutions, which completes in about 60 min under continuous mixing. In contrast, the amphiphilic ligand accelerates the halide exchange in 2-propanol, suggesting ambipolar functional groups speed up the ion-exchange reaction. The bromide vacancy-filled or halide-exchanged samples in a toluene–water biphasic solvent show higher stability than amphiphilic ligand-capped samples in 2-propanol. This strategy of defect passivation, ion exchange, and ligand chemistry to improve quantum yields and tune band gaps of halide perovskite nanocrystals can be promising for designing stable and water-soluble perovskite samples for solar cells, light-emitting diodes, photodetectors, and photocatalysts. 

Abstract

Cu-doped TiO2 with different weight percentages of Cu loading (1% to 4%) were synthesized by the sol–gel technique and characterized by powder XRD, SEM and TEM. 1 and 2 wt% Cu2+ doping, Cu -TiO2 has a major anatase phase with a minor rutile phase, and with increasing Cu loading to 3% and 4%, rutile phase increasing were observed. UV–Vis absorption spectroscopy confirmed that with Cu doping, the band gap of TiO2 decreased. PL and XPS was used to understand the optical properties and the surface elemental composition and the oxidation state of the elements of the prepared catalysts. Photocatalytic activity of synthesized materials was assessed for the visible light assisted removal of Rhodamine B and Cr (VI) individually and simultaneously. The mineralization of the pollutant was confirmed by the TOC analyzer. 3% Cu-doped TiO2 shows the highest degradation and mineralization when compared to other TiO2 materials. The radicals trapping experiments were conducted to determine the mechanism and it was found that O2–• and e- are the active radical species for the photocatalytic degradation of Rhodamine B and Cr (VI). The simultaneous removal of Rhodamine B and Cr (VI) was higher compared to the removal of individual pollutants.

Abstract

The unique and highly tunable photophysical, photochemical and photoredox properties of porphyrins contribute to their versatile applications in alternate energy generation, sensing, and therapeutic fields. The synthetic route for meso substituted porphyrins involves acid-catalysed condensation of aldehyde and pyrrole followed by oxidation. Herein, we report an environmentally benign novel approach for the synthesis of substituted tetraaryl porphyrins using acetonitrile as the solvent and Keggin type phosphovanadotungstic acid as the catalyst. The simple one-pot strategy completely avoids the usage of acidic/chlorinated solvents and expensive oxidising agents. A reasonable spectroscopic yield of around 12–39% could be obtained for various derivatives under the optimised conditions. 

Abstract

Eco-friendly carbothermal techniques were used to synthesize nanocomposites of biowaste-derived Ni/NiO decorated-2D biochar. The use of chitosan and NiCl2 in the carbothermal reduction technique was a novelty to synthesize the Ni/NiO decorated-2D biochar composite. Potassium persulfate (PS) was found to be activated by Ni/NiO decorated-2D biochar, which is thought to oxidize organic pollutants through an electron pathway designed by the reactive complexes formed between PS and the Ni/NiO biochar surface. This activation led to the efficient oxidation of methyl orange and organic pollutants. Analyzing Ni/NiO decorated-2D biochar composite before and after the methyl orange adsorption and degradation procedure allowed us to report on the process of its elimination. The Ni/NiO biochar with PS activation showed higher efficiency than Ni/NiO decorated-2D biochar composite as this material was able to degrade over 99% of the methyl orange dye. The effects of initial methyl orange concentration, dosages effect, solution pH, equilibrium studies, kinetics, thermodynamic studies, and reusability were examined and evaluated on Ni/NiO biochar. 

Abstract

The design and development of inexpensive, and extremely sensitive sensors for Hydroxylamine (HYA) are imperative due to its toxicity to animals, plants, and aquatic life. This work proposes a high-performance enzyme-free electrochemical sensor for HYA based on its oxidation on Nickel cobaltite (NCO) spinel-modified fluorine doped tin oxide (FTO) electrode. Hydrothermally grown irregularly shaped NCO nanoparticles (NPs) of size around 10 nm are characterized by XRD, XPS, UV–visible, BET, and TEM to evaluate the structural and morphological characteristics. NCO-modified FTO (NCO@FTO) electro-oxidizes HYA at a potential of 0.66 V vs. Ag/AgCl, delivering 1.7 times the current response than bare FTO. The rich catalytically active redox couples of Ni and Co, high conductivity, and high surface area of the NCO NPs contribute to the superior electrochemical response of NCO@FTO. As an amperometric sensor, NCO@FTO detects HYA in a wide range of 10 to 4000 µM concentration with a high sensitivity of 408 μA mM−1 cm−2. The sensor has a detection limit of 0.47 μM (S/N = 3), faster response of less than 3 s, excellent selectivity, and good stability. The practical feasibility of the proposed sensor is investigated by employing it in the monitoring of real samples. This study demonstrates NCO@FTO as an efficient low-cost sensor for HYA and extends the use of spinel metal oxides in bioanalysis.

Abstract

A coaxial dielectric barrier discharge (DBD) reactor was used to perform catalytic non-thermal plasma for CO2 conversion under ambient conditions. A systematic study was made to understand the role of basic oxides in activating weakly acidic CO2. For this purpose, MO/γ-Al2O3 (M = Mg, Ca, Sr, and Ba) catalysts were synthesized and integrated with the DBD reactor. The applied voltage was varied from 16 kV to 22 kV to determine the effect of applied voltage on CO2 conversion. Plasma discharge generates high-energy electrons that activate the basic oxides. Integration of basic metal oxides with the non-thermal plasma reactor resulted in a higher CO2 conversion. The adsorption of weakly acidic CO2 on the basic sites is responsible for the higher conversion of catalytic plasma reactor over plasma reactor alone. Among the basic metal oxides studied, SrO loaded γ-Al2O3 resulted in the best conversion, where CO2 conversion of ∼ 12% and energy efficiency of ∼ 1.46 mmol kJ−1 was attained at a power of 1.8 W. The concentration of O2 and O3 was measured during the reaction. The hybridized system's superior performance may be due to increased charge deposition and altered gas-phase chemistry because of catalyst integration. BOLSIG + software was used to compute the mean electron energies and electron energy distribution function for various packing conditions. 

Abstract

A set of mono and bimetallic Cu–Ni systems supported on γ-alumina catalysts were synthesized using γ-radiation instead of conventional calcination and reduction. Using a variety of characterization approaches, the structural and surface characteristics of catalysts were determined and their properties were compared with their counterparts prepared using the conventional method. The efficiency of these catalysts for the vapour phase selective hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) was investigated. The catalysts prepared by γ-irradiation contain Cu in its metallic state with high dispersion. γ-Radiation is advantageous because it enables the preparation of metal-supported catalysts in a single step by avoiding post-reduction. The catalysts prepared by γ-irradiation presented a higher activity compared to the conventional catalysts. Among all, the catalysts with 10%Cu–7%Ni on γ-Al2O3 demonstrated the highest conversion (94.5%) and selectivity (97%). The enhanced activity of the γ-irradiated catalysts was mostly attributable to the existence of a high surface area and copper dispersion. The γ-irradiated catalyst showed stable activity during the time of stream analysis. The desired reaction conditions to achieve a high yield of γ-valerolactone were also optimized. 

Abstract

Bandgap-engineered inorganic and hybrid halide perovskite (HP) films, nanocrystals, and quantum dots (PQDs) are promising for solar cells. Fluctuations of photoinduced electron transfer (PET) rates affect the interfacial charge separation efficiencies of such solar cells. Electron donor- or acceptor-doped perovskite samples help analyze PET and harvest photogenerated charge carriers efficiently. Therefore, PET in perovskite-based donor–acceptor (D–A) systems has received considerable attention. We analyzed the fluctuations of interfacial PET from MAPbBr3 or CsPbBr3 PQDs to classical electron acceptors such as 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 1,2,4,5-tetracyanobenzene (TCNB) at single-particle and ensemble levels. The significantly negative Gibbs free energy changes  of PET estimated from the donor–acceptor redox potentials, the donor–acceptor sizes, and the solvent dielectric properties help us clarify the PET in the above D–A systems. The dynamic nature of PET is apparent from the decrease in photoluminescence (PL) lifetimes and PL photocounts of PQDs with an increase in the acceptor concentrations. Also, the acceptor radical anion spectrum helps us characterize the charge-separated states. Furthermore, the PL blinking time and PET rate fluctuations (108 to 107 s−1) provide us with single-molecule level information about interfacial PET in perovskites. 

Abstract

Developing efficient photocathodes with novel design is essential for enhancing the functioning of photoelectrodes in photoelectrochemical (PEC) water splitting. The efficiency of solar-to-fuel conversion has been proven to be improved by using a suitable structural composition to create heterostructures. Apart from surface reactions, charge transfer between heterojunction interfaces is critically important. We report the first-ever novel and rational design of a hybrid photocathode using a CuBi2O4 based absorber material with a Sb2S3 heterojunction and evenly dispersed plasmonic Au nanoparticles (NPs) sandwiched between CuBi2O4 and Sb2S3. The heterostructure comprising CuBi2O4/Sb2S3 revealed an enhanced photoactivity due to ameliorated light absorption and charge separation showing a photocurrent density of −2.25 mA cm−2 at 0 V vs. RHE at pH 6.65. The crucial dual role of sandwiched Au NPs, as an electron relay mediator, facilitates the electron transfer at the heterojunction interface. Secondly, a plasmonic sensitizer enhances light absorption and charge carrier concentration via charge injection in CuBi2O4/Au/Sb2S3. The CuBi2O4/Au/Sb2S3 photocathode displayed a remarkable photocurrent density of −3.2 mA cm−2 at 0 V vs. RHE (0.85% HC-STH at 0.45 V vs. RHE) at pH 6.65, two-fold enhancement compared to CuBi2O4 (−1.5 mA cm−2 at 0 V vs. RHE, 0.27% HC-STH at 0.3 V vs. RHE). The high-performance CuBi2O4/Au/Sb2S3 photocathode achieves the highest photocurrent and HC-STH efficiency for a heterojunction to the best of our knowledge. Our findings will pave the way for developing new photoelectrodes with metal NPs sandwiched between semiconductor heterostructures and increasing PEC performance for solar-driven PEC water splitting.

Abstract

Biogas is a renewable energy produced due to the anaerobic decomposition of plants and animals. Biogas contains a high amount of methane (CH4), carbon dioxide (CO2), and trace amounts of hydrogen sulfide (H2S). It is naturally released in the environment, and the composition varies depending on the source it is generated. The primary focus of the study is to understand the influence of H2S on CH4 and CO2 conversion during syngas production. The effect of applied voltage on biogas reforming reaction with different dielectric materials (glass beads, γ-Al2O3, ZrO2, and quartz wool) packed in a discharge zone was investigated by using a dielectric barrier discharge (DBD) non-thermal plasma reactor. The influence of gas composition and packed bed on the efficiency of the biogas reforming reaction was investigated. After that, the biogas reforming reaction with packed dielectric material was performed without H2S and subsequently with H2S (blended with N2) while keeping the residence time constant. It was observed that H2S has a significant effect on the conversion. The CH4 conversion drastically dropped from 23% (without H2S) to 9% (with H2S), and CO2 conversion dropped from 18% to 11 % at 22 kV with quartz wool packed DBD. Energy efficiency decreased from 3.12 mmol/kJ (without H2S) to 1.78 mmol/kJ (with H2S) with glass beads packed DBD. Moreover, H2S has more effect on CH4 conversion than CO2. 

Abstract

Developing cost-effective noble metal-free co-catalysts as alternatives to platinum group metals is an impeccable strategy to enhance photoelectrochemical (PEC) water splitting. In this report, we successfully fabricated CuInS2 nanosheet array-based photocathode modified with CdS and co-catalyst MoS2 in a green approach to improve water splitting under solar irradiation. The visible light absorption of the modified hybrid photocathode (CIS/CdS/MoS2) was significantly enhanced due to introducing CdS and MoS2. Photoluminescence, impedance spectroscopy, and Mott–Schottky analysis depicted improved separation of excited electron–hole pairs, minimized resistance of charge transfer, and increased excited-state charge carrier concentration, resulting in increased photocurrent. Typical results indicated that composite photoelectrodes delivered higher photocurrent (−1.75 mA/cm2 at 0 V vs RHE) and HC-STH conversion efficiency (0.42% at 0.49 V vs RHE) than those of CIS and CIS/CdS photoelectrodes. This improved PEC performance is accredited to the synergetic impact of CdS in charge generation and transfer and MoS2 as a cocatalyst with active surface sites for proton reduction. This study not only reveals the promising nature of CuInS2-based light absorber photocathodes for solar energy utilization but also recommends the use of MoS2 as a cocatalyst for the proton reduction reactions for widespread applications in solar to hydrogen conversion. 

Abstract

The development of efficient H2O2 sensors is crucial because of their multiple functions inside and outside the biological system and the adverse effects that a higher concentration can cause. This work reports a highly sensitive and selective non-enzymatic electrochemical H2O2 sensor achieved through the hybridization of Co3S4 and graphitic carbon nitride nanosheets (GCNNS). The Co3S4 is synthesized via a hydrothermal method, and the bulk g-C3N4 (b-GCN) is prepared by the thermal polycondensation of melamine. The as-prepared b-GCN is exfoliated into nanosheets using solvent exfoliation, and the composite with Co3S4 is formed during nanosheet formation. Compared to the performances of pure components, the hybrid structure demonstrates excellent electroreduction towards H2O2. We investigate the H2O2-sensing performance of the composite by cyclic voltammetry, differential pulse voltammetry, and amperometry. As an amperometric sensor, the Co3S4/GCNNS exhibits high sensitivity over a broad linear range from 10 nM to 1.5 mM H2O2 with a high detection limit of 70 nM and fast response of 3 s. The excellent electrocatalytic properties of the composite strengthen its potential application as a sensor to monitor H2O2 in real samples. The remarkable enhancement of the electrocatalytic activity of the composite for H2O2 reduction is attributed to the synergistic effect between Co3S4 and GCNNS. 

Abstract

Toluene is a common solvent used in paints, pesticides, resins, etc. Although toluene is found in low concentrations in an indoor environment, long-term exposure to it is hazardous. This research aims to study toluene oxidation in a catalyst-packed dielectric barrier discharge (DBD) reactor designed to withstand high flow rates. The DBD reactor was packed with commercially available Al2O3 first and then with Mn and Co oxide-coated Al2O3. The surface modification of Al2O3 with transition metal oxides significantly improved the reactor's performance. At a power input of 20.3 W (equivalent to 13.0 J/l), MnO2/Al2O3 efficiently decomposed 50 ppm toluene (93%), and the corresponding CO2 selectivity was 57%. The in-situ breakdown of ozone, which leads to the formation of more reactive oxidants such as atomic oxygen, appears to make MnO2/Al2O3 better among the catalysts studied. The mean electron energies and the energy electron distribution function were calculated using the BOLSIG+ program. 

Abstract

The current research is focused on the decomposition of carbon dioxide (CO2) into carbon monoxide (CO) and oxygen (O2) in a non-thermal plasma reactor using dielectric barrier discharge (DBD) at ambient conditions. Pure CO2 was injected into the DBD reactor at a flow rate of 30 mL min-1, and the voltage was varied between 16 kV to 22 kV. The filamentary micro discharges generated during plasma has a significant effect on CO2 conversion. The effect of packing materials on CO2 conversion was investigated by packing non-catalytic materials such as quartz wool, glass capillary, glass wool, and glass beads in the discharge zone of the DBD reactor. Among the studied packing materials, quartz wool exhibited a maximum CO2 conversion of 9.3 % at a discharge power of 2.0 W and specific energy input (SEI) of 4.0 J mL-1. However, glass capillary exhibited the highest energy efficiency of 1.2 mmol kJ-1 at an SEI of 3.5 J mL-1. 

Abstract

Despite being the most favorable ammonia (NH3) gas sensors, metal oxide semiconductors fail to deliver high selectivity and room temperature (RT) sensing. Tuning the metal oxide with doping is an attractive way of overcoming these disadvantages. Herein, we report Mn-doped ZnO microspheres as promising sensors for highly sensitive and selective RT sensing of NH3. ZnO and 2 wt% Mn-doped ZnO microspheres were synthesized by a low-cost and fast solution combustion synthesis, and their structure, morphology, and gas sensing properties were investigated. Mn-doping resulted in a change in the lattice parameters, an increase in the oxygen vacancies, and surface acidity of ZnO as confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Temperature programmed desorption (TPD), respectively. Mn-doped ZnO showed a response (Ra/Rg) of 20.2 in 100 ppm NH3, which is significantly higher than ZnO. The sensor showed high selectivity, three times higher than that of ZnO, and good stability. Improvement in the sensing performance of Mn-doped ZnO is attributed to the increase in the defects and surface acidity with Mn-doping. 

Abstract

In this report, copper bismuth oxide (CuBi2O4), a ternary oxide is used for the electrochemical detection of 4-nitrophenol (4-NP). 4-NP is an organic pollutant which is extremely toxic and hazardous to environment. Herein, CuBi2O4 nanorods are prepared hydrothermally followed by electrode fabrication using drop casting method. Structural, morphological studies of CuBi2O4 and electrochemical characterizations pertaining to its performance for electrochemical detection of 4-NP are performed. The electrode has displayed the sensitivity of 56.16 μA μΜ−1 cm−2 with limit of detection (LoD) of 0.61 μM. It displayed high selectivity against several organic and inorganic interferences. The feasibility of CuBi2O4 modified electrode for real water samples is tested and obtained good recovery values. The detailed mechanism involved in the electrochemical detection of 4-NP is proposed and validated with computational studies. Density functional theory (DFT) calculations are performed on the optimized molecules involved in the electrochemical detection of 4-NP confirming CuBi2O4 acting as electron donor while 4-NP as electron acceptor. Further, natural bond orbital (NBO) calculations of 4-NP show a charge of − 0.251 a.u. on -NO2 group and + 0.251 a.u. on the rest of the molecule indicating 4-NP undergoes facile nucleophilic attack. The electrostatic potential (ESP) mapping of 4-NP blue shaded regions justifies its favorable behavior towards nucleophilic attack. Apart from this, UV-Vis spectroscopy is used to study the catalytic reduction of 4-NP using NaBH4. This study reveals that CuBi2O4 is promising material for the electrochemical detection of 4-NP. Also, further modifications of CuBi2O4 can be explored for electrochemical sensing and catalytic performance. 

Abstract

This study investigates the durability and leachate behaviour of an alkali-activated fly ash (FA) as a binder to stabilise expansive soils in deep-mixing applications. To activate FA, a liquid alkali activator (LAA) to binder ratio (LAA–FA) was introduced and varied from 1.0 to 1.5. The effects on swelling–shrinkage, consolidation and unconfined compressive strength (UCS) characteristics under wetting–drying cycles (durability) were studied on deep-mixed expansive soils. Leachate studies were conducted to determine the environmental impact of alkali-activated FA. Heavy metal and sodium ion concentrations were measured in each leachate cycle. To examine the permanent microstructural and phase changes in the mixes, scanning electron microscopy (SEM) and x-ray diffraction (XRD) studies were conducted. The swelling–shrinkage behaviour of soil could be marginally controlled for LAA/FA = 1.0 and 1.25 due to heavy weight loss during the wetting–drying cycles. However, even after 12 durability cycles, the UCS of soil with LAA/FA = 1.5 retained 1.0 MPa and showed non-critical swelling–shrinkage behaviour. The heavy metals and sodium ion concentrations were in acceptable range for LAA/FA = 1.25 and 1.5. XRD and SEM studies revealed that soil treated with a binder ratio of LAA/FA = 1.5, showed high crystalline peaks and aggregated structures 

Abstract

In chronic wounds, rapid identification of the bacterial type is critical for immediate clinical assessment. A novel, cost-effective, and label-free electrochemical nanobiosensor was developed with the help of an indigenously fabricated carbon paste working electrode to rapidly identify the bacterial type. The proposed platform made use of gold nanoparticles (AuNPs) to boost electrochemical activity, and the strong affinity of boronic acid moieties for diols allowed for detection and differentiation of gram + ve and gram -ve bacteria on the same platform. A scalable and robust miniaturized Electrochemical Cell (E-Cell) designed for the developed electrodes assisted in reducing sample waste, detection time, and Limit of Detection (LOD). Within 15 min, the proposed nano biosensing platform identified Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria with an excellent recovery rate for the blind samples. Because of its size and the extra lipopolysaccharides (LPS) layer containing diols, the bioelectrode demonstrated a superior response to E. coli, effectively distinguishing it from S. aureus. Furthermore, the proposed biosensing platform demonstrated an excellent shelf-life and reproducibility with acceptable selectivity and exhibited an excellent specificity towards bacteria, making it an ideal candidate for rapid identification of the bacterial type. 

Abstract

This paper reports a facile approach for the synthesis of graphene stabilised zero valent iron (nZVI) via carbothermal reduction method using bio-waste materials. X-ray photoelectron spectroscopy confirmed the formation of nZVI, which was further supported by magnetic susceptibility measurements. The process of Cr(VI) removal was revealed by analysing nZVI/graphene before and after the Cr(VI) adsorption process. nZVI/graphene reduces Cr(VI) to Cr(III), which was adsorbed on the graphene sheet, avoiding the passivation of nZVI. Graphene provides good electrical conductivity, skeletal support, and has long-term electron releasing characteristics, which can accelerate the reduction of Cr(VI) to Cr(III) and demonstrates a quick and high removal capacity of Cr(VI) from an aquifer. The influence of Cr(VI) initial concentration, adsorbent dosages, equilibrium studies, solution pH, kinetics, adsorption isotherms, and thermodynamic parameters was also investigated. 

Abstract

Hydrogen production through solar-driven water splitting is a promising approach and an alternative to the conventional steam reforming of natural gas and coal gasification. The growing energy demand and environmental degradation through carbon-emitting fossil fuels urge a transition in the usage of non-renewable to renewable sources of energy. The photocathodes in a photoelectrochemical (PEC) water-splitting cell are essential for the direct evolution of hydrogen. Among the known photocathodes, Cu-based p-type semiconducting materials are the most promising photo-absorber materials owing to their low-cost, low toxicity, natural abundance, suitable bandgaps, and favorable band edges for reduction. Moreover, the chemical stability and the rate of recombination significantly limit the longevity, the PEC performance, and practical applicability of Cu-based photocathodes. To overcome these problems, it is critical to have a thorough understanding of the constraints, improvement strategies, and an assessment of current developments in order to construct and design highly stable and efficient photocathodes. Here, in this review we have summarized the development of Cu-based metal oxide and sulfide photocathodes with the significant operational challenges and strategies that have successfully been employed to enhance the PEC performance. Furthermore, the emphasis is placed on recent reports and future perspectives regarding emerging challenges. 

Abstract

Environmental degradation due to the carbon emissions from burning fossil fuels has triggered the need for sustainable and renewable energy. Hydrogen has the potential to meet the global energy requirement due to its high energy density; moreover, it is also clean burning. Photoelectrochemical (PEC) water splitting is a method that generates hydrogen from water by using solar radiation. Despite the advantages of PEC water splitting, its applications are limited by poor efficiency due to the recombination of charge carriers, high overpotential, and sluggish reaction kinetics. The synergistic effect of using different strategies with cocatalyst decoration is promising to enhance efficiency and stability. Transition metal-based cocatalysts are known to improve PEC efficiency by reducing the barrier to charge transfer. Recent developments in novel cocatalyst design have led to significant advances in the fundamental understanding of improved reaction kinetics and the mechanism of hydrogen evolution. To highlight key important advances in the understanding of surface reactions, this review provides a detailed outline of very recent reports on novel PEC system design engineering with cocatalysts. More importantly, the role of cocatalysts in surface passivation and photovoltage, and photocurrent enhancement are highlighted. Finally, some challenges and potential opportunities for designing efficient cocatalysts are discussed. 

Abstract

In this report, CuBi2O4/Co3O4 has been used for the electrochemical detection of glucose. Herein, CuBi2O4 nanorods and Co3O4 has been hybridized with CuBi2O4 to form CuBi2O4/Co3O4 nanocomposite hydrothermally. CuBi2O4 and CuBi2O4/Co3O4 electrodes are fabricated by using drop casting method. Structural, morphological studies of CuBi2O4/Co3O4 and electrochemical characterizations pertaining to its performance in comparison to CuBi2O4 for electrochemical detection of glucose are performed and discussed elaborately. The detailed mechanism involved in the electrochemical detection of glucose is proposed. The electrode has shown the sensitivity of 49 μA mM−1 cm−2 with a limit of detection (LOD) of 0.136 μM. DFT calculations are performed on the optimized molecules involved in the electrochemical detection of glucose confirming CuBi2O4/Co3O4 acting as electron donor while glucose as electron acceptor. Further, natural bond orbital (NBO) for charge distribution calculations and ESP mappings for the optimized molecules are performed to understand nucleophilic/electrophilic positions. This study reveals that CuBi2O4 and its modifications are promising materials for the electrochemical detection of glucose. Further, the role of Co3O4 in improving the sensitivity and electrochemical performance for detection of glucose has been discussed. 

Abstract

The development of efficient and novel p-n heterojunctions for photoelectrochemical (PEC) water splitting is still a challenging problem. We have demonstrated the complementary nature of (p-type) BiSbS3 as a sensitizer when coupled with (n-type) TiO2/CdS to improve the photocatalytic activity and solar to hydrogen conversion efficiency. The as-prepared p-n heterojunction TiO2/CdS/BiSbS3 exhibits good visible light harvesting capacity and high charge separation over the binary heterojunction, which are confirmed by photoluminescence (PL) and electrical impedance spectroscopy (EIS). The ternary heterojunction produces higher H2 than the binary systems TiO2/CdS and TiO2/BiSbS3. This ternary heterojunction system displayed the highest photocurrent density of 5 mA·cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE) in neutral conditions, and STH of 3.8% at 0.52 V vs. RHE is observed. The improved photocatalytic response was due to the favorable energy band positions of CdS and BiSbS3. This study highlights the p-n junction made up of TiO2/CdS/BiSbS3, which promises efficient charge formation, separation, and suppression of charge recombination for improved PEC water splitting efficiency. Further, no appreciable loss of activity was observed for the photoanode over 2500 s. Band alignment and interfaces mechanisms have been studied as well.