Department of Chemistry

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Browsing Department of Chemistry by Author "Samant, Purnakala V."

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    Insitu FTIR studies for the enhanced activity of Pt(HY) and Pt-Ru(HY) zeolite catalysts for electrooxidation of methanol in fuel cells
    (Chemical Physics Letters, 2020) Samant, Purnakala V.; Fernandes, Julio B.
    Insitu FTIR (Fourier transform infrared spectroscopy) technique has been employed to study the oxidation of methanol on Platinum and Platinum - Ruthenium catalysts supported on HY zeolites [Pt-Ru (HY)/C]. The reaction has been studied by recording the spectra at different temperature ranges from room temperature till 170 °C. The catalytic activity has been studies in presence and absence of oxygen supply. The mechanism for oxidation of methanol has also been interpreted from the data obtained. The decomposition of methanol on Platinum (HY)/C catalyst occurs via carbonate/formate pathway in presence of oxygen and carbonate/carboxylate in absence of oxygen. The optimum efficiency of the Pt (HY) catalyst occurs at 120 °C. But on the surface of Pt- Ru (HY)/C catalyst, methanol oxidation occurs at room temperatures, thus emphasizing higher catalytic efficiency. The enhanced activity of the Platinum–Ruthenium/HY has been explained on the basis of intermediates formed during the reaction.
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    Thiourea modulated supercapacitive behavior of reduced graphene oxide
    (Diamond & Related Materials, 2024) Naik, Arti K.; Samant, Purnakala V.
    In this report, we investigated the role of the concentration of nitrogen and sulfur containing thiourea in modulating the electrochemical properties of reduced Graphene Oxide (rGO) by controlling the percentage of heteroatoms on the rGO surface. The synthesis route involved the preparation of Graphene Oxide (GO) using an improved method of synthesis in an economical way by reducing the volume of concentrated acids used. Furthermore, GO is reduced by using different mass proportions of thiourea via a simple reflux method. Characterization of the rGO samples by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDAX) and elemental analysis through CHNS analyzer exhibited successful doping and impact of nitrogen and sulfur atoms on the graphene framework. The comparative electrochemical performance from Cyclic Voltammograms (CV), Galvanostatic Charge Discharge (GCD) profiles and Electrochemical Impedance Spectroscopy (EIS) measurements on the various rGO samples revealed the superiority of 1:8rGO having 15.190 wt% of nitrogen and 26.849 wt% of sulfur and S/N ratio of 1.768, in delivering highest specific capacitance of 465.21 F·g−1 at 1 mV·s−1 scan rate with a remarkable cyclic stability exhibiting a capacitive retention of 119 % and offering lowest charge transfer resistance and diffusion resistance. The study also demonstrated detrimental effect of excess thiourea on electrochemical properties of rGO. This work suggests an effective and simple approach for optimizing the nitrogen and sulfur content in rGO to enhance its electronic properties using thiourea.