1. Journal Articles
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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(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 Zn: a versatile resonant dopant for SnTe thermoelectrics(2019) Bhat, D.K.; Shenoy, U.S.SnTe-based materials have been receiving increasing heed in the field of thermoelectrics (TEs) because of their tunable electronic structure. Until now, only In and Bi are reported to introduce resonance level in SnTe. In this work, for the very first time, we report Zn as a resonant dopant in SnTe using first-principles density functional theory calculations. We show that the resonant states introduced by Zn raises the heavy hole valence sub-band above light hole valence sub-band leading to both record high room temperature Seebeck coefficient (~127 ?VK?1 at 300 K) and figure of merit, ZT (~0.28 at 300 K) for SnTe-based materials. The transport properties calculated using Boltzmann transport equations predicts Zn-doped SnTe to be a promising TE material, further confirmed by experimental ZTmaximum of ~1.49 at 840 K and ZTaverage of ~0.78 with 300 K and 840 K as cold and hot ends, respectively. � 2019 Elsevier LtdItem Volumetric, refractometric, and excess properties of glycylglycine in aqueous FeCl2 solution at temperatures T = (288.15 to 318.15) K(2010) Santosh, M.S.; Bhat, D.K.; Bhatt, A.S.Densities and refractive indices have been measured for glycylglycine in aqueous FeCl2 solution as a function of concentration at T = (288.15 to 318.15) K. The apparent molar volumes and partial molar volumes were obtained from these density data. The limited partial molar expansivities have been calculated from the temperature dependence of the partial molar volume. The molar refractions were calculated from the experimental refractive index values for the studied mixture. The excess volumes and molar refractions were also calculated. The results are discussed in terms of molecular interactions. � 2010 American Chemical Society.Item Volumetric and ultrasonic investigation of glycylglycine in aqueous FeCl3 solutions(2010) Santosh, M.S.; Bhat, D.K.; Bhat, A.S.Viscosity, ultrasonic velocity and density measurements have been carried out for glycylglycine in aqueous FeCl3 solution as a function of molality at T=288.15 K, 298.15 K and 308.15 K. The experimental data have been used to derive properties such as isentropic compressibility (? S ), change in isentropic compressibility (?? S ), relative change in isentropic compressibility (?? S /? 0), apparent molar compressibility, volume and their limiting apparent molar quantities along with the constants S K, S V and viscosity B-coefficient. The obtained thermodynamic properties have been discussed in terms of molecular interactions. � 2010 Springer Science+Business Media, LLC.Item Vanadium-Doped SrTiO3 Nanocubes: Insight into role of vanadium in improving the photocatalytic activity(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 Solute-solvent interactions in aqueous glycylglycine-CuCl2 solutions: Acoustical and molecular dynamics perspective(2011) Santosh, M.S.; Lyubartsev, A.; Mirzoev, A.; Bhat, D.K.Acoustical and molecular dynamics studies were carried out to understand the various interactions present in glycylglycine-CuCl2 aqueous solutions. Amongst these interactions, hydrogen bonding and solute-solvent interactions have been highlighted in this study. The radial distribution function (RDF) was used to investigate solution structure and hydration parameters. Binding of Cu2+ with various polar peptide atoms reveals the nature and degree of binding. The formation of complex clusters between glycylglycine and water molecules increases the relaxation time. The first hydration shell considerably influences the structure of the second shell, facilitating the formation of an ordered hydrogen bonded network. Both experimental and theoretical results have proved to be efficient in analyzing the behavior of molecules and to give a clear idea on molecular interactions in solutions. 2011 Springer Science+Business Media, LLC.Item Synthesis of BaWO4/NRGO g-C3N4 nanocomposites with excellent multifunctional catalytic performance via microwave approach(2018) Sadiq, M.M.J.; Shenoy, U.S.; Bhat, D.K.Novel barium tungstate/nitrogen-doped reduced graphene oxide-graphitic carbon nitride (BaWO4/NRGO-g-C3N4) nanocomposite has been synthesized by a simple one-pot microwave technique. The synthesized nanocomposites are well characterized by diffraction, microscopic and spectroscopic techniques to study its crystal structure, elemental composition, morphological features and optical properties. The material prepared is tested for its performance as an electrocatalyst, photocatalyst and reduction catalyst. The nanocomposite catalyzed the photodegradation of methylene blue (MB) dye in 120 min, reduction of 4-nitro phenol (4-NP) to 4-amino phenol (4-AP) in 60 s, showed an impressive Tafel slope of 62 mV/dec for hydrogen evolution reaction (HER). The observed results suggest that the nanocomposite acts as an efficient multifunctional catalyst. The reported approach provides fundamental insights which can be extended to other metal tungstate-based ternary composites for applications in the field of clean energy and environment in the future. 2018, Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature.Item Refractive indices and isentropic compressibilities of glycylglycine- FeCl2 in aqueous ethanol mixtures(2010) Santosh, M.S.; Bhat, D.K.The density and refractive index studies have been carried out for glycylglycine-FeCl2 in aqueous ethanol mixtures at four different temperatures in the range T = (288.15 to 318.15) K. A comparative study of the refractive indices obtained experimentally and those calculated by means of Gladstone-Dale and Lorentz-Lorenz relation has been made. Among them, the Gladstone-Dale equation afforded similar values to those obtained experimentally. Isentropic compressibilities, -S, and excess molar isentropic compressibilities, KS,mE, were estimated using the Kirkwood model. Using the Redlich-Kister type equations, excess partial molar isentropic compressibilities, KS,iE, were also obtained. The observed negative values of KS,2E in the water-rich region are due to the structural disorderliness. As infinitely dilute water is hydrogen-bonded to ethanol and glycylglycine, the variation of strength of interaction is not sensed by KS,1E,?. 2010 American Chemical Society.Item Preparation and characterization of an all solid supercapacitor based on polyaniline-Al2O3 layer on aluminium alloy-Al-2024(2007) Kumar, M.S.; Bhat, D.K.The characteristics of an all solid state supercapacitor based on polyaniline (Pani)-Al2O3 coating on aluminium alloy 2024 (Al-2024) surface prepared by the constant current method have been investigated. Three stages are observed in the potential- electrolysis time relation for the simultaneous preparation of the dielectric layer and the conducting polymer on the aluminium foil. The deposition of polyaniline film has been confirmed by cyclic voltammetry. The solid state capacitor has been studied by AC impedance spectroscopy and the capacitive behaviour of the cell is discussed in terms of Nyquist plots, complex capacitance and complex power. The study revealed that the capacitor has comparatively good capacitance, ranging from 450 to 600nF/cm2, a low time constant and also very low resistance. The normalized reactive power, |Q|/|S| and active power |P|/|S| versus frequency plot for the solid state capacitor allow an overview of the whole frequency behaviour of the supercapcitors, ranging from a pure resistance at high frequency to a pure capacitance at low frequency. When a capacitor is used as a source stiffening capacitor and is buffering the supply by delivering initial current, a lower RC time constant allows delivering significantly more current. So this type of solid-state capacitor can be used for the DC-DC converter modules.Item Porous Graphene Wrapped SrTiO3 Nanocomposite: Sr-C Bond as an Effective Coadjutant for High Performance Photocatalytic Degradation of Methylene Blue(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.