Beyond Conventional Catalysts: Monoelemental Tellurium as a Game Changer for Piezo-Driven Hydrogen Evolution.

The increasing demand for clean hydrogen production over fossil fuels necessitates the development of sustainable piezoelectrochemical methods that can overcome the limitations of conventional electrocatalytic and photocatalytic approaches. In this regard, existing piezocatalysts face challenges related to their low piezoelectricity or active site coverage for hydrogen evolution reaction (HER). Driven by global environmental concerns, there is a compelling push to engineer practical materials for highly efficient HER. Herein, monoelemental 2D tellurium (Te) is presented as a class of layered chalcogenide with a non-centrosymmetric crystal structure (P3121 space group). The refined Te nanosheets demonstrate an unprecedented highly efficient H2 production rate ≈9000 µmol g-1 h-1 under ultrasonic mechanical vibration due to built-in piezo-potential in the system. The remarkable piezocatalytic performance of Te nanosheets arises from a synergistic interplay between their semi-metallic nature, favorable free energy landscape, enhanced electrical conductivity and outstanding piezoelectricity. As a proof of concept, the theoretical approach based on Density Functional Theory (DFT) validates the findings due to the gradual exposure of active sites on the Te nanosheets leading to a self-optimized catalytic performance for hydrogen generation. Therefore, mechanically driven Te emerges as a promising piezocatalyst with the potential to revolutionize highly efficient and sustainable technology for futuristic applications.

New process for conversion of hazardous industrial effluent of ceramic industry into nanostructured sodium carbonate and their application in textile industry.

Increase in industrialization as a tool to become global leader has led to an exponential rise in environmental pollution. The present study describes a process developed to extract nanocrystalline sodium carbonate from chemical industry effluents, which contributes to wealth creation from hazardous waste. Sodium carbonate is a high demand product because of its applications in detergents, dyeing, glass, and paper manufacturing. In the present work, we have extracted nanostructured sodium carbonate using industrial waste (alkaline solution of silicates, obtained from ceramic industry) and carbon dioxide (a major component of flue gas effluent from power plants). Here we have collected waste from ceramic industries, which is highly corrosive (pH 13-14) and disposal of such waste is dangerous to the environment and needs to be taken special care. Pure carbon dioxide has been purged in collected industrial waste to get nanoparticles and flakes structure of sodium carbonate at room temperature. The use of the nanostructured sodium carbonate in the dyeing of textiles was encouraging. Significantly, higher dyeing efficacy was observed compared to the fabric dyed in the absence of sodium carbonate (Na2CO3). The nanocrystalline particles show much better color strength than bulk sodium carbonate when K/S value was compared. Na2CO3 with the minimum particle size (26 nm) results in the maximum color strength (K/S = 14.49).

Mechanistic Insights for Photoelectrochemical Ethanol Oxidation on Black Gold Decorated Monoclinic Zirconia.

Surface decoration of metal oxides by metals for enhancing their electrocatalytic properties for organic conversions has attracted a lot of researchers' interest due to their high abundancy, inexpensiveness, and high stability. In the present work, a process for the synthesis of black gold (BG) using a citrate assisted chemical route and m-ZrO2 by a hydrothermal method at 200 °C has been developed. Further, different concentrations of black gold are being used to decorate the surface of zirconia by exploitation of surface potential of zirconia and gold surfaces. The catalyst having 6 mol % concentration of black gold shows excellent electrocatalytic activity for ethanol oxidation with low oxidation peak potential (1.17 V) and high peak current density (8.54 mA cm-2). The current density ratio (jf/jb) is also high (2.54) for this catalyst indicating its high tolerance toward poisoning by intermediate species generated during the catalytic cycle. The enhanced electrocatalytic activity can be attributed to the high tolerance of gold toward CO poisoning and high stability of the ZrO2 support. The black gold decorated zirconia catalyst showed enhanced activity during photoelectrochemical studies when the entire spectrum of light falls on the catalyst. Ultrafast transient studies demonstrated plasmonic excitation of metallic free electrons and subsequent charge separation in the black gold-ZrO2 heterointerface as the key factor for enhanced photoelectrocatalytic activity.

Extraction of nanostructured sodium nitrate from industrial effluent and their thermal properties.

This study describes a process of extraction of high purity sodium nitrate from corrosive chemical industry effluents. Here, we have designed a process to convert highly corrosive effluents of ceramic industries having pH ~13.1 into sodium nitrate nanoparticles. The extraction of sodium nitrate has been carried out via neutralization of industrial effluent by nitric acid. We have also studied the effect of low boiling point co-solvent during recrystallization of sodium nitrate. TEM studies of sodium nitrate extracted from the filtrate in the absence of co-solvent show the formation of nanoparticle of ~70 nm. Further, a drastic decrease in particle size to 10 nm has been observed when co-solvents (methanol, ethanol, and acetone) were used in combination with filtrate during the recrystallization process of sodium nitrate. Thermal properties of sodium nitrate extracted from filtrate have been investigated. Our result indicates that the nanoparticles extracted from filtrate having very high heat storage density (453 J/g) without hampering the melting point and boiling point of the materials. PRACTITIONER POINTS: The new chemical process has been developed to treat the industrial effluent Extraction of nanostructured sodium nitrate has been carried from industrial effluent The particle size of sodium nitrate drastically influenced by the used co-solvent for recrystallization The highest heat storage density is 453 J/g, which was obtained from the recrystallization of the filtrate.

Energy efficient electrodes for lithium-ion batteries: Recovered and processed from spent primary batteries.

In an attempt to develop low cost, energy efficient and advanced electrode material for lithium-ion batteries (LIBs), waste-to-wealth derived as well as value added spent battery materials as potential alternatives assume paramount importance. By combining the low lithiation potential advantages, one can arrive at energy efficient electrodes bestowed with cost effective and eco-friendly benefits required for practical LIB applications. In the present study, Zn and Mn-salts along with C were successfully extracted from the spent zinc carbon batteries through a simple and efficient hydrometallurgy approach and decomposed thermally to obtain ZnMn2O4 at 350 °C for 12 h and 450 °C for 3 h. Further, C-ZnMn2O4 nanocomposites were prepared and demonstrated for appreciable electrochemical performance in LIB assembly. Our results show that C-ZnMn2O4 composites prepared at 350 °C and 450 °C demonstrate better performance than pristine ZnMn2O4 anode due to the improved electronic conductivity rendered by the added carbon obtained from spent primary battery. In particular, C-ZnMn2O4 at 350 °C @12 h exhibits appreciable electrochemical performance by showing a stable and higher capacity of 600 mAhg-1 at a current density of 50 mAg-1 in the voltage range of 0.01-3.0 V and qualifies it as a better performing cost-effective anode for LIBs.

New approach for the transformation of metallic waste into nanostructured Fe3O4 and SnO2-Fe3O4 heterostructure and their application in treatment of organic pollutant.

Appropriate recycling of waste to reusable materials is much sought after in the scientific community to control the incessant rising pollution in environment due to insufficient management of waste materials. To address this issue, efforts were directed to obtain SnO2-Fe3O4 nanocomposites from scrap tin plated steel and the use of these composites for the degradation of organic pollutant. We have demonstrated a novel, efficient and facile hydrometallurgy approach for the extraction of iron from waste tin plated steel containers found in plenty in the common waste generated in society. The extracted iron has further been utilized for the preparation of SnO2:Fe3O4 nanocomposites with different compositions (SnO2:Fe3O4 ratio of 93.2:6.8, 85:15, 58:42 and 40:60) using hydrothermal route. The photocatalytic activities of nanocomposite were determined spectroscopically using Rhodamine-B (RhB) as a model dye. Our results indicate that among all the composites with SnO2 (85%):Fe3O4 (15%) exhibits the best photocatalytic efficiency under UV light whereas the composition of SnO2 (93.2%):Fe3O4 (6.28%) is the most efficient in visible light. The above visible light efficiency was supported by density functional theory (DFT) studies which suggest a small amount of pure Fe is present at the Sn sites in the nanocomposite, leading to the reduction in the band gap of the nanocomposite and resulting in absorption in the visible range. Thus, in the present study, we have shown a process of conversion of waste to nanomaterials and its utilization for treatment of organic pollutants.

Room temperature synthesis of a copper ink for the intense pulsed light sintering of conductive copper films.

Conducting films are becoming increasingly important for the printed electronics industry with applications in various technologies including antennas, RFID tags, photovoltaics, flexible electronics, and displays. To date, expensive noble metals have been utilized in these conductive films, which ultimately increases the cost. In the present work, more economically viable copper based conducting films have been developed for both glass and flexible PET substrates, using copper and copper oxide nanoparticles. The copper nanoparticles (with copper(I) oxide impurity) are synthesized by using a simple copper reduction method in the presence of Tergitol as a capping agent. Various factors such as solvent, pH, and reductant concentration have been explored in detail and optimized in order to produce a nanoparticle ink at room temperature. Second, the ink obtained at room temperature was used to fabricate conducting films by intense pulse light sintering of the deposited films. These conducting films had sheet resistances as low as 0.12 Ω/□ over areas up to 10 cm(2) with a thickness of 8 µm.

Novel borothermal process for the synthesis of nanocrystalline oxides and borides of niobium.

A new process has been developed for the synthesis of nanocrystalline niobium oxide and niobium diboride using an amorphous niobium precursor obtained via the solvothermal route. On varying the ratio of niobium precursor to boron and the reaction conditions, pure phases of nanostructured niobium oxides (Nb(2)O(5), NbO(2)), niobium diboride (NbB(2)) and core-shell nanostructures of NbB(2)@Nb(2)O(5) could be obtained at normal pressure and low temperature of 1300 °C compared to a temperature of 1650 °C normally used. The above borothermal process involves the in situ generation of B(2)O(2) to yield either oxide or diboride. The niobium oxides and borides have been characterized in detail by XRD, HRTEM and EDX studies. The core-shell structure has been investigated by XPS depth profiling, EFTEM and EELS (especially to characterize the presence of boron and the shell thickness). The niobium diboride nanorods (with high aspect ratio) show a superconducting transition with the T(c) of 6.4 K. In the core-shell of NbB(2)@Nb(2)O(5), the superconductivity of NbB(2) is masked by the niobium oxide shell and hence no superconductivity was observed. The above methodology has the benefits of realizing both oxides and borides of niobium in nanocrystalline form, in high purity and at much lower temperatures.