Faculty Publications
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Item Tuning the Photocatalytic Activity of SrTiO3 by Varying the Sr/Ti Ratio: Unusual Effect of Viscosity of the Synthesis Medium(American Chemical Society service@acs.org, 2018) Bantawal, H.; Shenoy, U.S.; Bhat, D.K.SrTiO3 nanostructures were successfully synthesized in various alcohols as cosolvent as well as surfactant by a facile solvothermal method. The as-synthesized catalysts were characterized by X-ray diffraction technique, scanning electron microscopy, energy-dispersive X-ray analysis, Brunauer-Emmett-Teller analysis, diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The possible formation mechanism of SrTiO3 in the presence of these alcohols is discussed, and the effect of these alcohols on the structure, Sr/Ti atomic ratio, and optical properties is related to the photocatalytic activity. First principles calculations were made use of to determine the effect of defects on the electronic structure and the band gap. The photocatalytic activity of these catalysts was evaluated by taking methylene blue as a model pollutant under visible light irradiation. It was found that the photocatalytic activity of ethanol-mediated SrTiO3 was found to be higher than the other samples because of the synergistic effect of high surface area and lesser defects. © 2018 American Chemical Society.Item Eco-friendly synthesis of porous graphene and its utilization as high performance supercapacitor electrode material(Elsevier Ltd, 2019) Sethi, M.; Bantawal, H.; Shenoy, U.S.; Bhat, D.K.The successful application of porous graphene (PG) is hindered due to the lack of efficient and cost-effective method for its synthesis. Herein, we report a facile and eco-friendly method to produce PG through a low temperature solvothermal method. The structural and morphological characteristics of PG samples were investigated thoroughly. The as synthesized material is found to be a few layers thick (?4–6 layers) with a surface area of 420 m2 g?1 and consisting of hierarchical pores on the surface of the sheets. A high specific capacitance of 666 F g?1 was obtained at a scan rate of 5 mV s?1, apart from longer cyclic stability with 87% retention of initial capacitance value after 10000 cycles for the PG 28 sample. The fabricated supercapacitor displayed an energy density of 26.3 Wh kg?1 and power density of 6120 W kg?1. Density functional theory calculations were also carried out to qualitatively support the enhanced capacitance by providing theoretical insight from electronic structure and density of states of PG. These results open a new avenue for greener synthesis of high-quality PG using environmentally friendly solvents, without the use of toxic chemicals, for excellent supercapacitor performance. © 2019 Elsevier B.V.Item Porous Graphene Wrapped SrTiO3 Nanocomposite: Sr-C Bond as an Effective Coadjutant for High Performance Photocatalytic Degradation of Methylene Blue(American Chemical Society service@acs.org, 2019) Bantawal, H.; Sethi, M.; Shenoy, U.S.; Bhat, D.K.Porous graphene-SrTiO3 (PGST) composite prepared by a facile solvothermal method was tested for its photocatalytic activity in degradation of methylene blue (MB) dye. First-principles density functional theory calculations were also carried out to study the effect of nanocomposite formation on the electronic structure and density of states. The combined experimental and theoretical study gave insights regarding the formation of the Sr-C bond which enhanced the charge transport, effectively separating the charge carriers and reduced their recombination rate. The formation of PGST nanocomposite favorably tuned the electronic structure with decreased band gap due to introduction of the hybridized states extending the absorption to the visible region of electromagnetic spectrum. The microscopy studies revealed loofah like PG wrapped SrTiO3 nano structures with contusions providing high surface area facilitating adsorption of MB dye. Degradation of ?92% was obtained by 7.5 PGST in 120 min with high cyclic stability indicating its suitability as an efficient photocatalyst for the treatment of pollutants. © 2019 American Chemical Society.Item Vanadium-Doped SrTiO3 Nanocubes: Insight into role of vanadium in improving the photocatalytic activity(Elsevier B.V., 2020) Bantawal, H.; Shenoy, U.S.; Bhat, D.K.SrTiO3 based materials have been gaining attention recently in the field of photocatalysis due to their tunable electronic structure. Herein, we employ a facile one pot solvothermal approach for the synthesis of V doped SrTiO3 nanocubes. First principles theoretical calculations reveal that the 3 'd' dopant level introduced by V reduces the band gap and extends the absorption to the visible region of spectrum. The occupancy of Ti site by V introduces dopant states overlapping with the conduction band, eliminating the formation of mid gap recombination centres. Photocatalytic experimental studies on degradation of methylene blue dye reveals the material to be an excellent photocatalyst with high photocorrosion resistance and cyclic stability. In addition, the material is also predicted to be a potential thermoelectric material. © 2020 Elsevier B.V.Item Rhodium doping augments photocatalytic activity of barium titanate: Effect of electronic structure engineering(Royal Society of Chemistry, 2020) Bhat, D.K.; Bantawal, H.; Shenoy, U.S.Environmentally friendly BaTiO3 is emerging as a potential photocatalyst due to its tunable electronic structure. Although originally believed to be a poor photocatalyst due to its wide band gap, several strategies have been implemented to reduce its band gap. One such approach is doping, but this often leads to the formation of mid gap recombination centers and diminishes the efficiency of the material. In the present work, we study for the first time the effect of site occupancy of Rh on the electronic structure of BaTiO3. As the theoretical results reveal that if Rh occupies both Ba and Ti sites simultaneously it leads to the formation of mid gap states, an experimental approach is implemented to reduce the band gap of BaTiO3 while simultaneously avoiding the formation of recombination centers. The facile one pot hydrothermal approach reported here directs the Rh towards Ba sites leading to a decrease in the band gap due to the appearance of donor Rh3+ states, suppressing the formation of Rh4+ states. A promising photocatalytic activity of 96% degradation of methylene blue dye in 120 minutes was observed for the 0.5 Rh sample indicating the high efficiency of the material. © The Royal Society of Chemistry.Item Vanadium doped CaTiO3cuboids: role of vanadium in improving the photocatalytic activity(Royal Society of Chemistry, 2021) Bantawal, H.; Shenoy, U.S.; Bhat, D.K.CaTiO3has attracted enormous interest in the fields of photocatalytic dye degradation and water splitting owing to its low cost, excellent physicochemical stability and structural tunability. Herein, we have developed a simple one pot solvothermal approach which directs V into the Ti sites in the isovalent state during the synthesis of V doped CaTiO3cuboids. The prediction of reduction in the band gap due to the formation of additional levels just beneath the conduction band edge by the first principles density functional electronic structure study is confirmed by the experimental results. The suppression of charge carrier recombination in 1.0 V leads to the highest photocatalytic activity in the degradation of methylene blue. The percentage degradation of 94.2 indicates its suitability as an excellent catalyst for photocatalytic water treatment. © The Royal Society of Chemistry 2021.