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Author: search.filters.author.Shetty K, V.Subject: search.filters.subject.Copper oxides

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    Visible light irradiated photocatalytic reduction of CO2 to hydrocarbons using hybrid polyaniline/ CuO nanocomposite in aqueous system
    (Taylor and Francis Ltd., 2022) Matthew, D.; Shetty K, V.
    The ever-increasing energy demand has resulted in an increase in CO2 emissions and global warming. Photocatalytic reduction of CO2 to methanol, which is considered to be the next generation alternate fuel is gaining interest to combat global warming and to move towards a methanol economy. The present work focuses on photocatalytic reduction of CO2 using Polyaniline/CuO (PANI/CuO) nanocomposite to methanol, formic acid, and formaldehyde under visible light irradiation. CuO nanoparticles were synthesised using the aqueous extract of Tectona grandis (teak) leaves and further used in the synthesis of PANI/CuO nanocomposite with different CuO loading. PANI/CuO nanocomposite exhibited visible light activity in the reduction of CO2 to form methanol, formic acid, and formaldehyde. Photocatalytic reduction of CO2 with PANI/CuO nanocomposite containing 13.7% by weight of CuO resulted in a maximum yield of methanol. The band gap energy of the nanocomposite was found to be 2.28 eV, thus confirming its good visible light activity and the PANI-CuO heterojunction-based mechanism of photocatalysis is proposed. The synthesis of PANI-CuO photocatalyst uses CuO which is synthesised by an eco-friendly route with the utilisation of teak leaves, a timber industry waste and thus it can serve as a greener catalyst. © 2022 Indian Institute of Chemical Engineers.
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    Extracellular synthesis of heteroatom doped copper oxide nanoparticles from electronic waste – Transforming waste to resource for the remediation of nitrophenol contaminated water
    (Elsevier Ltd, 2024) Sophia, S.; Shetty K, V.
    Industrial effluents containing hazardous phenolic compounds such as 4-nitrophenol (4-NP) can threaten aquatic ecosystems and the environment. To address the environmental issues due to nitrophenol-contaminated industrial effluents and rapidly generating electronic waste (e-waste), catalytic nanoparticles are biosynthesized utilizing the waste printed circuit boards (WPCBs) and the cell-free supernatant (CFS) of the bacteria Alcaligenes aquatilis for the catalytic reduction of 4-NP with sodium borohydride (NaBH4). The optimum synthesis parameters to maximize 4-NP reduction were an initial pH of 12.4 and a volume ratio of metal leachate to CFS of 1:3. These nanoparticles were found to be heteroatom-doped CuO/Cu2O (Bio-CuO/Cu2O-PCB) with spherical shape, average crystallite size of 19 nm and average particle size of 19.2 nm. The biosynthesized nanoparticles exhibited excellent catalytic activity in the reduction of 4-NP with a pseudo-first-order rate constant (kapp) of 0.526 min-1, induction period of 2 min, and 90% reduction of 4-NP in 6 min. This work demonstrates the recovery of metal resources from waste as nanoparticles with excellent catalytic activity using a green, eco-friendly synthesis method under ambient conditions. Bio-CuO/Cu2O-PCB showed better activity than commercial CuO, biosynthesized and chemically synthesized CuO using precursor salt. The developed synthesis method is eco-friendly and could yield a recyclable catalyst for reducing harmful aromatic pollutants such as 4-NP present in wastewater to 4-aminophenol, a pharmaceutical intermediate. © 2024 Elsevier Ltd
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    Extracellular biosynthesis of CuO-TiO2 nanocomposites using Alcaligenes aquatilis for the photodegradation of reactive and azo dyes under visible light irradiation
    (Springer, 2025) Agarwalla, S.; Shetty K, V.
    In this study, CuO/TiO2 nanocomposites were biologically synthesized using cell-free supernatant (CFS) of Alcaligenes aquatilis growth culture by two-step synthesis method, one-pot method with sequential addition of precursors, and one-pot method with simultaneous addition of precursors. The one-pot method with simultaneous addition of precursors was found to be the best method for the synthesis in terms of degradation of reactive blue-220 (RB-220) and acid yellow-17 (AY-17) dyes under visible light irradiation. CuO/TiO2 nanocomposite was found to have the crystallite size of 14.7nm and the bandgap energy of 2.5 eV. The effect of synthesis parameters such as synthesis time, pH of CFS, and the ratio of Cu to Ti in the synthesis mixture on the photocatalytic degradation efficacy of these nanocomposite structures under visible light irradiation was studied. The optimum conditions for the synthesis of CuO/TiO2 nanocomposite particles by one-pot method with simultaneous addition of precursors were found to be pH 12 of CFS, synthesis duration of 24 h, and molar ratio of Cu to Ti in the synthesis mixture as 1:22 for RB-220 dye and 1:25 for AY-17 degradation. CuO/TiO2 nanocomposite particles synthesized under the optimum conditions and without any calcination could degrade RB-220 and AY-17 dyes completely in 120 min and 150 min, respectively. The kinetics of degradation of RB-220 and AY-17 by CuO@TiO2 nanocomposite particles followed first-order kinetic model with rate constant of 0.028 min?1 and 0.018 min?1, respectively. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.