Faculty Publications
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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.Item Electronic structure engineering of BaTiO3 cuboctahedrons by doping copper to enhance the photocatalytic activity for environmental remediation(Elsevier Ltd, 2023) Uma, P.I.; Shenoy, U.S.; Bhat, D.K.The advent of perovskites as an efficient photocatalyst has paved the way to newer possibilities in the degradation of contaminants such as dyes and toxic heavy metal ions. The alleged poor photocatalyst BaTiO3 was engineered to perform better by decreasing its bandgap to make it visible light active via doping. The high-risk factor in the reduction of the bandgap is the formation of recombination centers for the charge carriers which decreases the efficiency of the photocatalyst. Herein, we studied the electronic structure tuning of BaTiO3 by doping copper and developed a one pot synthesis method to obtain copper doped BaTiO3 that has a high surface area, lower recombination rate, and higher photocatalytic efficiency towards dye degradation and hexavalent chromium ion reduction. The 0.5 CuBT sample had a photocatalytic efficiency of 99.4 % for methyl violet decomposition within 120 min and 99.8 % for hexavalent chromium ion reduction by fructose in 20 min. © 2023 Elsevier B.V.Item Nanocubic Copper-Doped SrTiO3 for Photoreduction of Cr(VI) and Photodegradation of Methyl Violet(American Chemical Society, 2023) Uma, U.; Shenoy, U.S.; Bhat, D.K.Visible light photocatalysis using nanomaterials is a pragmatic approach for efficiently eliminating pollutants as environmental pollution is a major stumbling block. The wide band gap of SrTiO3 is permuted to an appropriate value by adding a suitable dopant to make it function as a visible light photocatalyst. Nanocubic copper-doped strontium titanate was prepared through a single-pot solvothermal route and tested for its photocatalytic activity. An exceptional 99% photoreduction of Cr(VI) ions to Cr(III) within 15 min and 100% in 25 min and 99% photodegradation of the methyl violet dye within 120 min was observed for the 0.5 CuST sample. First principles density functional theory calculation reveals the reduced band gap of the doped samples due to the introduction of additional energy levels above the valence band edge to be the reason behind the increased photocatalytic efficiency. In addition to this, the three-fold increase in surface area and low recombination rate of charge carriers in the doped nanocubes also favor in enhancing the activity. © 2023 American Chemical Society.Item Enhanced photoresponse and efficient charge transfer in porous graphene-BaTiO3 nanocomposite for high performance photocatalysis(Elsevier Ltd, 2023) Bhat, D.K.; Bantawal, H.; Uma, U.; Shenoy, U.S.Porous graphene-BaTiO3 (PGBT) nanocomposite was synthesized by a simple one pot solvothermal method and its photocatalytic activity was evaluated by studying its efficiency in degrading methylene blue (MB) dye under visible light. The combination of experimental and theoretical analysis revealed enhanced photocatalytic activity of the PGBT composite, which could be attributed to (i) the interaction of BaTiO3 nanoparticles with PG sheets via Ba–C bond, (ii) reduced band gap due to the introduction of hybridized states leading to increased absorption in visible range and (iii) large surface area which provides more active sites for the efficient adsorption of MB dye. The formation of Ba–C bond proved to be highly advantageous for the efficient transport of photogenerated charge carriers, thereby suppressing the recombination of charge carriers. The synthesized nanocomposite showed three times higher photodegradation efficiency compared to BaTiO3. In addition to this, the composite also showed an excellent cyclic stability indicating its suitability as an effective photocatalyst for the environmental remediation. © 2023 Elsevier B.V.Item Copper doping induced band structure and morphology transformation in CaTiO3 for textile dye photodegradation applications(Elsevier Ltd, 2024) Shenoy, U.S.; Uma, P.I.; Bhat, D.K.Semiconductor metal oxides with a wide bandgap like CaTiO3 can be exploited into an efficient visible light photocatalyst via cation doping. The type of dopant and the site of doping is known to greatly influence the photocatalytic activity of a material. Based on the intricacies of the density functional theory electronic structure study, we delve into the optimization of one-pot solvothermal synthesis to obtain Cu doped CaTiO3 nanocuboids. Doping of copper not only resulted in change in the electronic structure of the material but also led to change in the morphology. The uneven nanostep architecture resulted in increase in the surface area of the catalyst, which led to more active sites for the adsorption of the dyes and subsequent degradation. The reduced band gap and decreased recombination of charge carriers made the copper doped calcium titanate an efficient photocatalyst for degradation of both cationic (99.7% degradation of MV dye in 120 minutes) and anionic (99.8% degradation of RB in 45 minutes) dyes. © 2024 Elsevier B.V.Item Exceptional light harvesting in copper doped CaTiO3 nanocuboids with surface nanosteps for the photo remediation of toxic Cr(VI) ions and dyes(Elsevier B.V., 2024) Bhat, D.K.; Uma, P.I.; Shenoy, U.S.Addressing the rising concerns of water pollution caused by harmful inorganic and organic contaminants is very crucial and photocatalysts with exceptional light harvesting capability are a promising way to tackle these issues. This study investigates the transformation of CaTiO3 into a visible light-active photocatalyst via copper doping. Copper-doped CaTiO3 nanocuboids were synthesized via a one-step solvothermal approach, resulting in the formation of distinctive nanostep substructures on the surface. Morphological analysis revealed the successful incorporation of copper ions into the perovskite matrix, as evidenced by the transition from smooth to rough, uneven surface features. X-ray diffraction confirmed the incorporation of Cu2+ ions into the Ti4+ site, while visible range absorption indicated a reduction in the bandgap. Furthermore, doping decreased the rate of charge carrier recombination and increased their average lifetime, prolonging the duration of active species. This modification facilitating efficient absorption of visible light and increase in the charge separation, leads to enhanced photocatalytic activity. The doped catalyst exhibited exceptional performance in the remediation of hexavalent chromium ions (98.5 % Cr6+ ions reduction to Cr3+ ions in 20 min), methylene blue (99.4 % degradation within 120 min), and eosin yellow (99.8 % degradation within 80 min) pollutants. This research underscores the potential of doping as a viable strategy for tailoring photocatalytic properties and addressing water pollution challenges. © 2024 Elsevier B.V.