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Synthesis of NIR active Inorganic Pigment
NIR (Near-Infrared) active inorganic pigments refer to pigments that exhibit absorption or reflectance in the near-infrared region of the electromagnetic spectrum. These pigments find applications in various fields, including coatings, paints, plastics, textiles, ceramics, and security inks. Here is a description of NIR active inorganic pigments:
Composition: NIR active inorganic pigments are typically composed of metal oxides or mixed metal compounds. Examples include iron oxide (Fe2O3), chromium oxide (Cr2O3), cobalt aluminate (CoAl2O4), copper chromite (CuCr2O4), and various other metal-based compounds.
NIR Absorption/Reflectance: NIR active inorganic pigments possess specific optical properties that allow them to absorb or reflect near-infrared light. These pigments are designed to interact with light in the range of approximately 700 to 2500 nanometers (nm).
Color Variations: NIR active inorganic pigments can exhibit different colors, including shades of red, brown, green, blue, or black. The specific color depends on the composition and crystal structure of the pigment, as well as the presence of impurities or dopants.
Stability and Durability: NIR active inorganic pigments are known for their excellent stability and durability. They offer resistance to light, heat, chemicals, weathering, and other environmental factors, ensuring their long-term performance in various applications.
NIR Sensing and Imaging: NIR active inorganic pigments find applications in NIR sensing and imaging technologies. These pigments can absorb or reflect NIR light, enabling their use as contrast agents in NIR fluorescence imaging, security inks for anti-counterfeiting measures, or as markers for NIR-based sensors and detectors.
Heat Management: Some NIR active inorganic pigments possess heat management properties due to their NIR absorption characteristics. They can absorb NIR radiation and convert it into heat, making them suitable for applications such as solar control coatings, thermal barrier coatings, or temperature-regulating materials.
Energy Applications: NIR active inorganic pigments are utilized in energy-related applications. They can be used in solar energy harvesting systems as NIR-absorbing materials, enhancing the conversion of NIR light into usable energy. Additionally, these pigments can be employed in thermal management applications to control heat absorption and dissipation.
Non-Toxicity and Safety: Many NIR active inorganic pigments are known for their non-toxic nature and are considered safe for use in various applications. However, it is essential to consider specific regulations and guidelines regarding their use in different industries to ensure their safe incorporation.
Compatibility and Formulation: NIR active inorganic pigments can be incorporated into various formulations, such as paints, coatings, plastics, or textiles, to achieve desired NIR properties and coloration. Proper dispersion techniques and formulation considerations are necessary to ensure uniform distribution and stability in the final product.
Research and Development: Ongoing research focuses on exploring new compositions, structures, and synthesis methods to further enhance the NIR absorption or reflectance properties of inorganic pigments. This includes the development of novel dopants, surface modifications, or nanostructured pigments to achieve desired optical and functional characteristics.
By harnessing the unique properties of NIR active inorganic pigments, researchers and industries can expand their capabilities in sensing, imaging, energy applications, heat management, and coloration, catering to the evolving needs of various sectors.
Here is the list of synthesized NIR active Inorganic Pigment
Production of Hydrogen Gas via Electrocatalysis and Photocatalysis way
Electrocatalysis refers to the use of catalysts to lower the activation energy required for an electrochemical reaction. In the case of hydrogen gas production, electrocatalysts play a crucial role in facilitating the electrochemical splitting of water molecules into hydrogen (H2) and oxygen (O2) gases.
The hydrogen evolution reaction occurs at the cathode, where water molecules are reduced to produce hydrogen gas. Electrocatalysts, often based on metals or metal alloys, are employed to enhance the reaction kinetics and improve the efficiency of hydrogen gas generation. Common catalysts used for HER include platinum (Pt), nickel (Ni), cobalt (Co), and their various combinations.
The production of hydrogen gas via electrocatalysis and photocatalysis involves using catalysts to drive the electrochemical or photochemical reactions that generate hydrogen from a suitable source, such as water. Here is a description of these two methods:
Electrocatalysis:
Electrocatalysis involves using catalysts to facilitate the electrochemical splitting of water into hydrogen and oxygen gases through water electrolysis. The process occurs in an electrolytic cell with two electrodes, an anode and a cathode, separated by an electrolyte.
a. Catalysts: Electrocatalysts, typically based on metals or metal oxides, are used to lower the energy barrier for the water splitting reaction. Common electrocatalysts for hydrogen evolution include platinum (Pt), nickel (Ni), cobalt (Co), or their alloys. These catalysts provide active sites for the electrochemical reactions and enhance the reaction kinetics.
b. Proton Exchange Membrane (PEM) Electrolysis: In PEM electrolysis, a proton exchange membrane is placed between the anode and cathode compartments. The anode facilitates the oxidation reaction (generating oxygen), while the cathode promotes the reduction reaction (generating hydrogen) by attracting protons and electrons.
c. Alkaline Water Electrolysis: In alkaline water electrolysis, an alkaline electrolyte, typically potassium hydroxide (KOH) or sodium hydroxide (NaOH), is used instead of a proton exchange membrane. The alkaline environment promotes the dissociation of water molecules, facilitating the hydrogen and oxygen evolution reactions.
Photocatalysis:
Photocatalysis involves using a photocatalyst to harness light energy and initiate the chemical reactions required for hydrogen generation from water. The process relies on the absorption of photons by the photocatalyst, which leads to the formation of electron-hole pairs and subsequent redox reactions.
a. Catalysts: Photocatalysts used for hydrogen production are typically semiconductors, such as titanium dioxide (TiO2), strontium titanate (SrTiO3), or tungsten trioxide (WO3). These materials have suitable energy band structures that allow them to absorb light and facilitate the necessary electron transfer reactions.
b. Water Splitting Reaction: Photocatalysts absorb photons with energy equal to or greater than the bandgap energy, promoting electron excitation from the valence band to the conduction band. This creates electron-hole pairs, and by employing suitable co-catalysts and sacrificial electron donors or acceptors, the excited electrons and holes can participate in redox reactions that split water into hydrogen and oxygen gases.
c. Photocatalytic Systems: Photocatalysis for hydrogen production can be carried out in various systems, including slurry systems where the photocatalyst is dispersed in a liquid suspension, fixed-bed reactors where the photocatalyst is immobilized on a solid substrate, or photoelectrochemical cells where the photocatalyst is integrated with appropriate electrodes and electrolytes.
d. Optimization: Researchers focus on optimizing the photocatalyst's composition, morphology, and surface properties to enhance light absorption, charge separation, and reaction efficiency. Additionally, efforts are made to explore cocatalysts, co-catalyst deposition methods, and strategies for suppressing charge recombination to improve overall photocatalytic activity.
Both electrocatalysis and photocatalysis provide promising routes for sustainable hydrogen production. These methods offer clean and renewable pathways for generating hydrogen, a versatile energy carrier, with the potential to contribute to the development of clean energy systems and address the challenges of energy storage and environmental sustainability.
Graphene based supercapacitor
A graphene-based supercapacitor is a type of energy storage device that utilizes graphene as a key component to store and deliver electrical energy efficiently. Graphene, a two-dimensional carbon material with exceptional electrical conductivity and surface area, offers unique advantages for supercapacitor applications. Here is an overview of graphene-based supercapacitors:
Graphene as an Electrode Material: Graphene serves as an ideal electrode material for supercapacitors due to its high electrical conductivity, large surface area, and mechanical strength. Graphene electrodes can store electrical charge in the form of electrostatic double-layer capacitance and/or pseudocapacitance, resulting in high energy and power densities.
Graphene Structure: Graphene is composed of a single layer of carbon atoms arranged in a hexagonal lattice. Its two-dimensional nature provides a large surface area for charge storage, allowing for more efficient charge transfer and increased capacitance.
Graphene Composite Electrodes: Graphene can be combined with other materials, such as metal oxides, conductive polymers, or carbon nanotubes, to form composite electrodes. These composites enhance the electrochemical performance of supercapacitors by increasing the specific capacitance, improving charge storage mechanisms, and enhancing stability.
Fabrication Techniques: Various techniques are employed to fabricate graphene-based supercapacitors. These include solution-based methods like chemical vapor deposition (CVD), chemical reduction of graphene oxide, electrodeposition, or inkjet printing. These methods enable the deposition of graphene films or patterns on substrates, making them suitable for scalable production.
High Energy and Power Density: Graphene-based supercapacitors exhibit high energy and power densities compared to traditional capacitors due to the high surface area of graphene electrodes. This allows for efficient charge accumulation and rapid charge/discharge cycles.
Fast Charge/Discharge Rates: Graphene's excellent electrical conductivity enables rapid charge and discharge rates in supercapacitors, making them suitable for applications that require quick energy delivery, such as regenerative braking systems, portable electronics, or energy storage for intermittent renewable sources.
Long Cycle Life: Graphene-based supercapacitors have excellent cycling stability and long cycle life due to the mechanical flexibility and structural integrity of graphene. This means they can endure numerous charge/discharge cycles without significant degradation, ensuring their durability over extended usage.
Environmental Friendliness: Graphene-based supercapacitors offer environmental benefits as they are typically free from toxic materials. Graphene itself is a carbon-based material and does not contain harmful substances, making it a more sustainable and eco-friendly choice for energy storage.
Future Advancements: Ongoing research focuses on improving the performance of graphene-based supercapacitors by optimizing graphene synthesis techniques, exploring advanced electrode architectures, and developing novel electrolytes. These advancements aim to enhance energy density, power density, and overall device performance.
Graphene-based supercapacitors hold great promise for energy storage applications, offering high power, long cycle life, and environmental sustainability. With continued research and development, graphene-based supercapacitors could contribute to the advancement of various fields, including electric vehicles, renewable energy systems, portable electronics, and smart grid technologies.