Publications

The valorization of industrial byproducts is a crucial step towards sustainable production. Sotol bagasse, a lignocellulosic residue from Sotol spirit production, is a promising feedstock for biorefineries. This study aimed to optimize microwave-assisted pre-treatment of sotol bagasse biomass for fermentative lactic acid production using a microbial consortium from cow manure. Microwave irradiation was employed to hydrolyze the complex structure of the Sotol bagasse, releasing fermentable sugars. Notably, these pre-treatments were more selective than traditional acid hydrolysis, minimizing the formation of inhibitory compounds like hydroxymethylfurfural. Instead, microwave pre-treatments promoted levulinic acid formation through autohydrolysis driven by steam explosions, a valuable chemical platform for various industrial applications. The optimal microwave pre-treatment conditions that led to almost pure glucose attaining a 3 % w/w efficiency in converting lignocellulose to glucose resulted in a maximum lactic acid production of 9.6 g/L. This study demonstrates the potential of Sotol bagasse as a sustainable feedstock for lactic acid production, contributing to a more circular economy. 

Developing efficient energy storage devices is crucial in a growing trend toward using electromobility and renewable energy sources. This study focuses on preparing environmentally friendly supercapacitors by synthesizing activated carbon decorated with semispherical CaS nanoparticles of approximately 30 nm in size. Pecan nutshells (Carya illinoinensis) were used as a carbon and calcium source, whereas (NH4)2SO3 was used both as a novel activating agent and a CaS precursor, enabling the formation of CaS-decorated activated carbons, as discussed in this work, for the first time. Activated carbon was prepared using a high-flux solar radiation furnace (SF) and a conventional tube furnace (TF). The synthesis temperature and concentration of the activating agent were determined using a factorial experimental design with central set points at 400, 600, and 800 °C and 1, 2, and 3 M. Physicochemical analysis revealed that temperature had a statistically significant effect on the surface area and degree of graphitization of the synthesized materials only when the TF method was used. The carbonaceous materials were electrochemically characterized in a 3-electrode cell to investigate their energy storage properties as supercapacitor electrodes. The highest electrochemical capacitance (≈180 Fg−1) was obtained in a potential window of 2 V. In addition, the best carbon-based material was tested as a supercapacitor electrode and exhibited a specific energy of 14.42 Wh/kg, increasing by 50 % after 15,000 cycles, highlighting its electro-activation characteristics. Even though metal sulfides have been extensively used for supercapacitors, this is the pioneering work harnessing biomass-derived carbons decorated with calcium sulfide nanoparticles for supercapacitors. 

Electrochemical energy conversion and storage devices are pivotal in transforming our society and advancing sustainability. Therefore, educating students in electrochemistry, the fundamental backbone of these technologies, is essential for preparing a new generation of professionals and raising public awareness of the role of these technologies in mitigating environmental challenges. However, a critical challenge lies in teaching electrochemistry through captivating and interactive approaches, particularly for younger learners. Herein, we outline a week-long workshop designed to immerse high school and undergraduate students in the world of electrochemical energy conversion and storage. The workshop was meticulously crafted to ensure a comprehensive exploration of electrochemistry fundamentals, operational principles of energy devices, real-world applications, and their societal impacts. Through mini-lectures, demonstrations, class discussions, educational games, and collaborative projects based on active learning, this workshop aims to improve the students’ understanding of electrochemistry and promote an appreciation for its critical role in society. Course evaluations indicate that our approach cultivates a stimulating learning environment. This initiative serves as a model for future educational programs in electrochemistry, aiming to equip students with the knowledge and inspiration needed to contribute to a sustainable future. 

Sotol bagasse is an increasing waste. This is due to the growing demand for sotol liquor in Mexico. By now, it pollutes the environment with no other use. In terms of sustainable development, the safe reuse of waste and biomass is expected. Additionally, the overexploitation of aquifers and natural leaching processes have caused an increase in the concentration of arsenic in drinking water. This work aims to characterize sotol bagasse and its conversion into a biochar. Additionally, it assesses the biochar´s suitability for removing arsenic from water. Ash, extractives, and lignin content of sotol bagasse were 7.40, 11.57, and 29%. Scanning electron microscopy revealed a fibrous structure with carbon, oxygen, calcium, and potassium. Bagasse was pyrolyzed from 300 to 900 °C. Infrared spectroscopy analysis indicated biopolymer degradation according to temperature. The highest biochar yield was 46.69%. The largest surface area was 77.59 m2/g. The biochar efficiently removed arsenic (97% at eight h) from Chihuahua’s city tap water, with an initial concentration of 0.026 mg/L. X-ray photoelectron spectroscopy showed calcium within the biochar framework is essential for arsenic removal. 

Among hybrid and all-inorganic halide perovskites, CsSnI3 has stood out with moderate electrical conductivity and ultralow thermal conductivity. Nevertheless, the former is still low compared to values of traditional thermoelectric materials, this makes its applications scarce. Herein, we wish to present a DFT study combined with the application of the Boltzmann transport equation, to determine the effects of p and n-type substitutional doping in the lattice structure, electronic and thermoelectric properties of CsSn0.75A025I3 (A = B, Sb). Our calculations show that doping increases the thermoelectric power factor to 181.2 µW m−1 K−2 under Sb-doping, which represents a twofold value compared to 78.3 µW m−1 K−2 of the pristine lattice; under B-doping we obtained a value of 145.6 µW m−1 K−2. CsSnI3 has higher power factor upon n-type doping. Finally, yet importantly, we further examine the shifts in the Fermi level using the effective mass model framework. In doing so, our work predicts a performance enhancement by achieving a Fermi energy level close to the VBM, or CBM. Similarly, our work demonstrates that doping represents an effective way to improve the thermoelectric power factor of CsSnI3, this being attributed to the increase of charge carriers and the modification of the band structure. 

This study presents a physico-chemical characterization of bagasse obtained from the artisanal and industrial production of Sotol. The last was employed as feedstock for acetone-butanol-ethanol (ABE) fermentation using Clostridium beijerinckii. Chemical analyses revealed a significant presence of CaC₂O₄, and levels of inorganic elements close to or above the limits established in ISO 16968:2015. These, together with their calorific values that are below other lignocellulosic materials, limit the use of sotol bagasse as solid biofuel. Structural characterization exhibited that the industrial sotol bagasse contained cellulose with lower crystallinity, thus easing its bioavailability for microorganisms to perform ABE fermentation. It was possible to obtain acetone, butanol, and ethanol (0.94 ± 0.05 g/L, 1.97 ± 0.52 g/L and 1.90 ± 0.40 g/L, respectively) using industrial sotol bagasse as substrate for C. beijerinckii. Then a scale-up of ABE fermentation was carried out to obtain information on ABE yield and Clostridium growth kinetics at different working volumes. ABE yield was lower the scale-up experiment (0.31 ± 0.02 g/g) compared to the obtained with smaller working volume (0.48 ± 0.07 g/g). These results offer crucial insights into the potential use of industrial sotol bagasse as a novel renewable feedstock to obtain biofuels throughout ABE fermentation.

We present the effect of sodium ions (Na+) on the nucleation process and phase selectivity for the formation of hexagonal molybdenum trioxide crystals (h-MoO3). The phase selectivity during the reaction is attributed to the interaction of Na+ with the molecules in our precursor solution formed by metallic molybdenum dissolved in a mixture of hydrochloric and nitric acids. The vibrational characteristics of the precursor solutions were studied by Raman spectroscopy in combination with density functional theory modeling, showing the presence of [MoO2Cl3(H2O)]− ions within the solutions. The symmetric stretching vibration of the Mo–O bonds found at 962 cm–1 in [MoO2Cl3(H2O)]− proved that the addition of Na+ (in the form of dissolved NaCl) to the precursor solutions resulted only in an electrostatic interaction with the aquo (H2O) and chloro (Cl–) ligands in the complex. After heating the precursor solutions, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy of the obtained powders showed that adding NaCl contributed to the phase selectivity of the reaction, with the Na+ ions playing a vital role in the formation of h-MoO3 over other crystalline phases. Based on the nature of the molybdenum complexes found in the precursor solutions and the structural characteristics of the powders, a formation mechanism to obtain h-MoO3 is proposed. Additionally, the phase stability of h-MoO3 crystals was studied by calorimetry techniques, showing that h-MoO3 transforms to α-MoO3 at ∼649 K. These results provide important insights into phase control to selectively form hexagonal MoO3. 

Coal consumption has led to a worrying surge in flue gas emissions, aggravating health and environmental issues worldwide. Therefore, novel approaches supported by sustainable technologies are needed to exploit flue gas emissions effectively. Here, we evaluate an ammonia-based flue gas desulfurization process based on the photochemical capture of CO2 and SO2 for producing hydrogen and ammonium-based fertilizers. The kinetics and mechanistic pathways for sulfite photooxidation are examined, while process feasibility and environmental relevance are evaluated by process simulation and life cycle assessment. Results show that increasing the initial sulfite concentration results in faster reaction rates, following first-order kinetics with an activation energy of 32.9 kJ/mol. Moreover, kinetics is ascribed to two competing photoinduced radical-mediated reaction pathways. Finally, powering the process by renewable energy leads to positive human health, ecosystems, and resources scores in life cycle assessment, supporting the sustainability of the process. Overall, this approach offers essential insights for large-scale hydrogen production through the photooxidation of captured flue gas emissions. 

The study evaluated the spatial and seasonal variations of microplastic abundances in water, sediments, and commercial fishes of a semi-urban tourist impacted estuary in the Gulf of Mexico, Mexico. The prevalence of microplastics (MPs) elucidated diffuse sources namely long-range transport, domestic, agricultural, fishing, industrial and recreational activities and the local climatic conditions. Seasonally, the mean abundances of MPs in both water and sediments were high during Nortes (strong winds) followed by the dry and rainy seasons. Overall, black and blue colored MPs dominated the region and all the recovered plastics were fibers. The commercial fishes (n = 187) contained 881 MPs in their gastrointestinal tracts, suggesting that the food web of the estuary is highly prone to microplastic contamination. SEM images of extracted plastic fibers presented surface morphologies that are impacted by physical strains. Further, the elemental characterization of fibers using EDX displayed significant peaks of Al, As, Cl, Cr, Cu, Pb, and Zn that were used as additives during the production of plastics. The main types of polymers included low-density polyethylene, polyester, polypropylene, polycarbonate, rayon, polyvinyl chloride, polyacrylonitrile, polyamide, nylon and polyethylene terephthalate. MP abundances demonstrated in this study elucidate that estuaries are a major conduit for land-derived plastics to the ocean and the results will aid in implementing remedial/clean up actions of the estuary for better conservation of the ecosystem.

Electrochemical water splitting is one of the most promising approaches for sustainable energy conversion and storage toward a future hydrogen society. This demands durable and affordable electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In this study, we report the preparation of uniform Ni–P–O, Ni–S–O, and Ni–S–P–O electrocatalytic films on nickel foam (NF) substrates via flow cell-assisted electrodeposition. Remarkably, electrodeposition onto 12 cm2 substrates was optimized by strategically varying critical parameters. The high quality and reproducibility of the materials is attributed to the use of a 3D-printed flow cell with a tailored design. Then, the as-fabricated electrodes were tested for overall water splitting in the same flow cell under alkaline conditions. The best-performing sample, NiSP/NF, required relatively low overpotentials of 93 mV for the HER and 259 mV for the OER to produce a current density of 10 mA cm−2. Importantly, the electrodeposited films underwent oxidation into amorphous nickel (oxy)hydroxides and oxidized S and P species, improving both HER and OER performance. The superior electrocatalytic performance of the Ni–S–P–O films originates from the unique reconstruction process during the HER/OER. Furthermore, the overall water splitting test using the NiSP/NF couple required a low cell voltage of only 1.85 V to deliver a current density of 100 mA cm−2. Overall, we demonstrate that high-quality electrocatalysts can be obtained using a simple and reproducible electrodeposition method in a robust 3D-printed flow cell. 

Nickel nitride (Ni3N) is known as one of the promising precatalysts for the electrochemical oxygen evolution reaction (OER) under alkaline conditions. Due to its relatively low oxidation resistance, Ni3N is electrochemically self-oxidized into nickel oxides/oxyhydroxides (electroactive sites) during the OER. However, we lack a full understanding of the impact of the effect of Ni3N self-oxidation and Fe impurity incorporation from electrolyte towards OER activity. Here, we report on our examination of the compositional and structural transformation of Ni3N precatalyst layers on Ni foams (Ni3N/Ni foam) during extended periods of OER testing in Fe-purified and unpurified KOH media using both a standard three-electrode cell and a flow cell, and discuss their electrocatalytic properties. After the OER tests in both KOH media, the Ni3N surfaces were converted into amorphous, nano-porous nickel oxide/oxyhydroxide surfaces. In the Fe-purified electrolyte, a decrease in OER activity was confirmed after the OER test because of the formation of pure NiOOH with low OER activity and electrical conductivity. Conversely, in the unpurified electrolyte, a continuous increase in OER activity was observed over the OER testing, which may have resulted from the Fe incorporation into the self-oxidation-formed NiOOH. Our experimental findings revealed that Fe impurities play an essential role in obtaining notable OER activity using the Ni3N precatalyst. Additionally, our Ni3N/Ni foam electrode exhibited a low OER overpotential of 249 mV to reach a geometric current density of 10 mA·cm−2 in a flow cell with unpurified electrolyte. 

The electrochemical oxidation of sulfite ions offers encouraging advantages for large-scale hydrogen production, while sulfur dioxide emissions can be effectively used to obtain value-added byproducts. Herein, the performance and stability during sulfite electrolysis under alkaline conditions are evaluated. Nickel foam (NF) substrates were functionalized as the anode and cathode through electrochemical deposition of palladium and chemical oxidation to carry out the sulfite electro-oxidation and hydrogen evolution reactions, respectively. A combined analytical approach in which a robust electrochemical flow cell was coupled to different in situ and ex situ measurements was successfully implemented to monitor the activity and stability during electrolysis. Overall, satisfactory sulfite conversion and hydrogen production efficiencies (>90%) at 10 mA·cm–2 were mainly attributed to the use of NF in three-dimensional electrodes with a large surface area and enhanced mass transfer. Furthermore, stabilization processes associated with electrochemical dissolution and sulfur crossover through the membrane induced specific changes in the chemical and physical properties of the electrodes after electrolysis. This study demonstrates that NF-based electrocatalysts can be incorporated in an efficient electrochemical flow cell system for sulfite electrolysis and hydrogen production, with potential applications at a large scale. 

Flow devices fabricated by means of 3D-printing offer an economic and effective approach for testing different electrochemical systems at laboratory scale. Here, the fabrication and optimization of a novel filter-press electrochemical reactor is described. 3D-printing is used to obtain critical components of the device as a sustainable and efficient manufacturing approach. Hydrodynamics and mass transfer of different flow distributors, turbulence promoters and nickel foam as three-dimensional electrode were evaluated by a convenient set of well-known techniques for filter-press reactor characterization. Furthermore, chemical stability of 3D-printed materials was assessed in several electrolytes used for common electrochemical applications. Designed configurations and geometries exhibited enhanced turbulence and large mass transfer coefficients, which make them adequate for processes such as electrosynthesis, electrodeposition and electrochemical water splitting. Ultimately, superior performance was validated for nickel foam, demonstrating robustness of the reactor for realistic evaluation of electrocatalytic materials. Therefore, the proposed electrochemical reactor provides a low-cost and versatile alternative for testing electrochemical systems in a wide range of applications. 

Dietary supplements may contain heavy metals with the property of bioaccumulation in humans. The aim of this research was to validate and apply two analytical methods to determine Pb, As, Cr, and Hg in dietary supplements by Total Reflection X-ray Fluorescence Spectroscopy (TXRF). Methods validation was conducted through a multivariate analysis using a central composite design (CCD) and a desirability function. Critical values for each study variable were established. The TXRF_DS_1 method was proposed for Pb, As, and Cr determinations, while the TXRF_DS_2 was established for Hg analysis. The digestion method with an acid mixture (HNO3 + HCl + H2O2) was used to break down the organic material of dietary supplements. A solution of 10 μg L−1 Ga was used as an internal standard. Excellent analytical performance was obtained as LODs of 0.59, 0.41, 0.57, and 0.75 μg L−1 and LOQs of 1.95, 1.35, 1.90, and 2.50 μgL −1 for Pb, As, Cr, and Hg, respectively. Calibration curves showed a good linearity for all elements (R2>0.999). Excellent accuracy and precision in measurements (% RSD) was achieved. The real and spiked samples analysis demonstrated the applicability of the TXRF technique (percentage recovery 91–108%). Besides, two samples were analyzed in a comparison study between the TXRF_DS_1 method and the ICP-OES method. The results obtained showed good agreement between both techniques. The TXRF technique allows the analysis of toxic heavy metals in dietary supplements, which are marketed in a wide variety of presentations. 

Sulfur-based thermochemical cycles, such as the hybrid sulfur-ammonia (HySA) cycle, offer a valuable approach in which hydrogen is produced by exploiting sulfur dioxide (potentially pollutant emissions) through the electrochemical oxidation of aqueous sulfite. In this study, the effect of pH on electrooxidation rate was assessed by comparing different reaction scenarios. Then, a Central Composite Design (CCD) combined with a Response Surface Methodology (RSM) was used to optimize batch electrooxidation of ammonium sulfite at near-neutral pH. Results show that the use of an anion exchange membrane (AEM) greatly improves sulfite electrooxidation rate while pH is effectively stabilized. Furthermore, a second-order model that relates applied potential and sulfite concentration with the normalized half-life of the reaction was obtained and verified experimentally at long-term batch electrooxidations. A good agreement between the model and experimental tests, adequate hydrogen recoveries and low sulfur crossover through the membrane demonstrate practical robustness of this approach. 

Electrochemical oxidation of sulfite ions offers an efficient and profitable approach to the conversion of sulfur dioxide, a harmful air pollutant, into valuable by-products via flue gas desulfurization. Here, the electrochemical oxidation of sulfite in near-neutral pH electrolytes is studied in order to determine kinetic parameters and a reaction mechanism. Sulfite electrooxidation on palladium is demonstrated at pH 7.5 and 8.5, the latter being comparable to platinum. Anodic charge transfer coefficients and non-linear reaction orders are linked to a mechanism which involves sulfite adsorption at low potentials. This study proves that sulfite electrooxidation on palladium at near-neutral pH is a useful approach for sulfur dioxide exploitation. 

Activated carbons are key electrode materials for supercapacitors (SCs) widely used in commercial devices. Here we investigate the preparation of activated solar carbons (ASCs) from pecan nutshell waste for their use as electrode materials for SCs. The ASCs are prepared using a sustainable process where concentrated solar energy is used as heat source for the one-step carbonization/chemical activation using H3PO4. From physical characterization we observed that our prepared ASCs are amorphous carbons, which have well-developed microporous surface of different features related with a pretreatment of pecan nutshell. The ASCs are electrochemically evaluated by cyclic voltammetry in four aqueous electrolytes using a three-electrode system, obtaining capacitances at 5 mVs−1 of 150 and 129 Fg-1 in acidic (0.5 M H2SO4) and environmentally-friendly neutral (1 M CH3COONa) electrolytes, respectively. Finally, we assembled asymmetric carbon-carbon SC cells showing excellent performance compared to a commercial activated carbon, with capacitances around 30 Fg-1 at 0.5 A g−1 with only ∼10% of capacitance loss after 5000 cycles, reveling a high stability, and a widest voltage window with the 1 M CH3COONa electrolyte. Our study provides a novel sustainable approach to use agricultural waste biomass to produce useful electrode materials for energy storage devices using concentrated solar energy.

Thermochemical water splitting cycles (TWSCs) are processes with the potential for large-scale production of carbon-free hydrogen. Among these, the sulfur-family thermochemical cycles are considered the most promising due to both, the use of readily affordable chemical reagents and the temperature required to thermally decompose oxygenated sulfur compounds, which is achievable by solar means. Indeed, solar heat assisted metal sulfate decomposition is a key step, where catalysis can be employed to reduce decomposition temperature. Here we present a green route to synthesize Ag-Pd and Fe-Pd intermetallic alloy catalysts supported over γ-Al2O3 and Si-C by a microwave-assisted method using glycerol both as a solvent and as a reducing and stabilizing agent. The obtained supported catalysts were physicochemically characterized. Fe-Pd/Al2O3 catalyst exhibited the best performance, abating the zinc sulfate decomposition temperature by ca. 85 °C in comparison with other reported catalysts 

Bioelectrochemical systems are devices where organic matter (e.g. wastewater) is oxidized through exoelectrogenic bacteria; this process is a new alternative to energy crisis and to mitigate climate change. If the products of such oxidation are electrons they are called microbial fuel cell (MFC), otherwise if the product is hydrogen these devices are called microbial electrolysis cells (MEC) Mostly, MEC's studies have reported double chamber designs, where the anode and cathode are separated by an ion exchange membrane. Nafion is a proton exchange membrane widely used to study bioelectrochemical devices; however, to our knowledge there are no reports of bipolar membranes (BPM) in these systems. In this study, a double-chambered MEC was constructed to evaluate the performance of the system using Nafion® 117, and FUMASEP®FBM bipolar membrane, separately. Biofilm formation was monitored by cyclic voltammetry and open circuit potential (OCP); maximum power for MFC-Nafion and MFC-BPM were 105.1 and 3.6 mW/m2, respectively. Hydrogen yield and COD removal were significantly different for both MEC systems. Whereas COD removal for MEC-BPM was 44.8%; MEC-Nafion exhibited a COD removal of 87.4%. Solely the latter system produced hydrogen, with a yield of 7.6%. 

Er3+/Yb3+ co-doped tellurite glasses (83-x)TeO2–10Nb2O5–5Al2O3–xTiO2–1Er2O3–1Yb2O3 where x=0, 2.5, 5, 7.5 and 10 mol% were fabricated by the conventional melt quenching technique. The structural, thermal and optical properties of the tellurite glasses were studied in dependence of the TiO2 concentration. All samples exhibit an amorphous structure which was modified by the introduction of TiO2 according to the X-Ray Diffraction (XRD) and Raman spectroscopy results. Differential scanning calorimetry (DSC) shows that the glass transition temperature and thermal stability increases with the addition of TiO2. The highest value of glass transition temperature (Tg) was 722 K which is one of the highest values found in the literature. On the other hand, the thermometric properties of two representative samples were studied by the fluorescence intensity ratio (FIR) technique. The maximum sensor sensitivity was 4.48 x 10–3 *K–1 at the 490 K temperature for sample with 5 mol% of TiO2 and 5.94 x 10–3 *K–1 at the 480 K temperature for sample with 7.5 mol% of TiO2 corresponding to 32% increase in the maximum sensor sensitivity by increasing TiO2 concentration. These results suggest that the presented host matrix is a good candidate for high temperature sensing applications. 

Lactose is recovered by crystallization from cheese whey that is a by-product of cheesemaking. The whey used for the recovery of lactose usually has a residual content of protein that alters the crystallization of lactose. In addition, the pH of whey may fluctuate depending on the cheese variety. However, there is little information on how the pH modifies the effect that whey proteins have on lactose crystallization. Accordingly, this work aimed to evaluate the individual and combined effect of whey proteins and pH on the kinetics of crystallization, the crystal size distribution and the crystallinity of lactose. The addition of whey proteins in lactose solutions (25% v/v) modified the process of lactose crystallization. However, the effect that whey proteins had on lactose crystallization heavily depended on the pH. The number of crystals per milliliter as well as the growth and size distribution of crystals was the most affected with the changes in pH (pHs of 7, 5.5 and 4) and the addition of whey proteins (0 and 0.63%). All the treatment produced mostly α-lactose monohydrated but some treatments also generated crystals of β-lactose (pH 5.5, 0% of proteins). Amorphous lactose was observed mainly in lactose solutions adjusted at pH 7 and added with whey proteins. This particular treatment also incorporated the highest amount of protein into the lattice of lactose crystals. The results of this work highlight the importance of controlling the pH of lactose crystallization, especially if there is a presence of whey proteins. 

Lead and chromium contamination represents one of the most serious problems in the aquatic environments. The aim of this work was to develop and validate an accurate, sensitivity, and rapid method for the simultaneous determination of Pb and Cr at trace levels in tissues and fat of marine organisms such as turtle (Chelonia mydas), shark (Rhizoprionodon terraenovae), and dolphin (Tursiops truncatus), utilizing the total reflection X-Ray fluorescence (TXRF) spectroscopy. Working solutions were prepared in 10 mL of a solution 0.005 mol·L−1 EDTA and 1 mol·L−1 HNO3. In order to correct possible instrument drifts, 20 μg·L−1 of gallium was used as internal standard (IS). The results showed that TXRF method was linear over the concentration ranges of 5.242–100 μg·L−1 for Pb and 2.363–100 μg·L−1 for Cr. Limits of detection (LOD) achieved were 1.573 and 0.709 μg·L−1 for Pb and Cr, respectively, while limits of quantification achieved were 5.242 μg·L−1 for Pb and 2.363 μg·L−1 for Cr. The validated method was accurate and precise enough for determination of these heavy metals in samples of marine organisms as indicated by acceptable values of recovery between 90–101%. In addition, a certified reference material (BCR-279, sea lettuce) and a Centrum tablet were satisfactory analyzed, and the T-test for comparison of means revealed that there were no significant differences at the 95% confidence level between the values obtained with the proposed TXRF method and the certificated values. The repeatability of the method, expressed as relative standard deviation (RSD), was 5.1% and 4%, for Pb and Cr, respectively. In addition, other features of the developed method were a low sample volume of 10 μL, and the sample frequency achieved was 20 h−1.

A rapid and sustainable route for synthesizing a green photocatalyst based on nanometric Cu2O clusters dispersed on TiO2 (≈ 2 wt%) was developed. These nanoclusters were synthesized using reducing sugars (0.85 wt%) from aqueous onion waste (Allium cepa) as reducing and stabilizing agent. All this under microwave irradiation. Green photocatalysts produced hydrogen through glycerol photoreforming, ca. 4.7 mmol H2/gcat. The recyclability and reusability of these materials were demonstrated and the achieved heterojunction between Cu2O and TiO2 exhibited a bandgap within the visible spectrum at 2.80 eV, showing potential feasibility to solarize this process. 

The sulfur-ammonia (SNH3) cycle uses the entire solar radiation spectrum to split water. It uses the UV radiation to promote the photolytic oxidation of ammonium sulfite to produce hydrogen and ammonium sulfate. Here, Raman and inelastic neutron scattering spectra of (NH4)2SO3·H2O at 20 K are discussed, supported by density functional theory (DFT) calculations. The feasibility of photolytic oxidation of this monohydrate to produce hydrogen at room temperature was also demonstrated. 

Palladium-based electrocatalysts are widely used in alkaline direct alcohol fuel cells. The synthesis and characterization of carbon-supported bimetallic nanoparticles (NP) of AuPd and AgPd is described using pecan nutshell extract (Carya illinoinensis) which serves as both, reducing and the stabilizing agent. This environmentally friendly route generates bimetallic NP for a wide range of applications, including electrocatalysis; since particularly AuPd NP proved to be a potentially suitable electrode material for alkaline direct methanol fuel cells. The electrocatalytic activity of these nanomaterials was comparable to commercially available Pd/C 1% in the electro-oxidation of methanol in alkaline media.