Faculty Publications
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Item Application of Prigogine-Flory-Patterson theory to volumetric, ultrasonic, and compressibility parameters of (glycylglycine + CuCl2) in aqueous ethanol mixtures(2011) Santosh, M.S.; Bhat, D.K.The molar volume and compressibility of (glycylglycine + CuCl2) in aqueous ethanol mixtures have been obtained at four different temperatures T = (288.15 to 318.15) K from ultrasonic velocity and density measurements. Excess molar volumes were found to be negative throughout the composition range indicating notable changes in hydrogen bonding and electrostatic interactions. Using the Prigogine-Flory-Patterson theory, quantitative estimation of different contributions, i.e. interactional, free volume, and P effect to VE have been obtained. The molar isentropic compressibility has been computed using the ultrasonic velocity and excess volume data. The trends in ?SE are affected by the size of the molecule leading to negative contributions. In order to compare the theoretical values of ultrasonic velocity, the equations of Nomoto and Junjie were used and found to predict the experimental data very well. © 2011 Elsevier Ltd. All rights reserved.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 A direct approach towards synthesis of copper nanofluid by one step solution phase method(Elsevier B.V., 2024) Kumar, S.P.; Shenoy, U.S.; Bhat, D.K.We adopted a simple one step approach to synthesize copper nanofluids by reduction of copper sulphate with fructose. The solution phase synthetic technique led to the formation of copper particles whose size was restricted to the nanodimensions by use of sodium lauryl sulphate. We studied the effect of various parameters on the formation and dispersion of the copper nanoparticles in the base fluid containing a 1:1 mixture of water and ethylene glycol. The resulting Newtonian nanofluid was found to be highly stable with increased thermal conductivity. Thus, the applied technique is found to be simple, economic, and extendable to other class of materials to obtain stable dispersions of nanofluids for heat transfer applications. © 2024 Elsevier B.V.Item Design, synthesis, and characterization of stable copper nanofluid with enhanced thermal conductivity(Elsevier Ltd, 2024) Bhat, D.K.; Kumar, S.P.; Shenoy, U.S.Nanofluids, which are liquids that contain small particles with dimensions in the nanometer range, have gained significant attention in recent years due to their enhanced thermal properties in various applications such as thermal management and energy conversion. This article aims to provide insights into the design and optimization of copper nanofluid synthesis and it investigates the thermal and rheological properties at varying concentrations of nanoparticles and temperature. The method involves simultaneous use of fructose as reducing agent and polyvinyl pyrrolidone as stabilizing agent to enable synthesis of copper nanofluid from copper sulphate. The resulting Newtonian nanofluid had a stability of 3 months with enhanced thermal conductivity of up to ∼500 % compared to 1:1 mixture of water and ethylene glycol which served as the base fluid. The approach is suitable for producing large volume of nanofluid using cost effective materials. © 2024 Elsevier LtdItem 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.