Browsing by Author "Naik, Arti K."

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    Experimental validation of vapor-phase direct methanol fuel cell with Pt-Ru/Zeolite electrocatalyst
    (Elsevier, 2025) Naik, Arti K.; Samant, Purnakala V.; Mordekar, Rajashri Karmali
    This study investigates the performance of a vapor-phase Direct Methanol Fuel Cell (DMFC) utilising a Pt-Ru/Zeolite (Pt-Ru/HY) electrocatalyst. The anode material, loaded with 2 wt% metal supported on zeolite (HY), demonstrates superior output voltage and power density compared to conventional Pt/C catalysts inspite of lower noble metal dosage. A Nafion membrane, operating under humidified conditions, effectively enhances proton conductivity and serves as a solid electrolyte. To comprehensively understand fuel cell behavior, a mathematical model is executed for theoretical calculation of diffusion, conductivity, permeability, and Nafion proton conductivity. Experimental validation is conducted by systematically varying operating conditions such as methanol concentration, flow rate, pre-humidified and dehumidified oxygen pressure, and temperature. The study reveals the significance of humidifying both the anode and cathode compartments for reducing voltage losses and increasing power output without much fuel loss. The obtained polarisation curves closely resemble those of traditional DMFCs, confirming the catalyst's effectiveness. Furthermore, the stability of the Pt-Ru/HY catalyst is consistent with reduced ohmic losses, indicating its durability for long-term operation.
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    Rationally designed NixOMS-2 nanostructures for enhanced bifunctional methanol oxidation and oxygen evolution electrocatalysis
    (Elsevier, 2026) Naik, Arti K.; Samant, Purnakala V.
    Addressing the global energy transition requires highly efficient, earth-abundant multifunctional electrocatalysts to replace scarce and precious materials for clean energy generation and storage applications like Methanol Oxidation Reaction (MOR) in fuel cells and Oxygen Evolution Reaction (OER) for water splitting. Current MnO2 based systems suffer from sub-optimal activity and poorly defined active sites. We present a rational synthesis utilizing facile reflux and precise thermal engineering to develop advanced Nickel-substituted Octahedral Molecular Sieves (NixOMS-2) nanostructures. Systematic optimization identified Ni0.03OMS-2 calcined at 400oC (NMB400) as the optimal catalyst exhibiting superior bifunctional performance and exceptional durability, achieving a peak MOR current density of 60.62 mA.cm−2 and an OER overpotential of 461 mV at 10 mA.cm−2, significantly surpassing most monofunctional MnO2 based catalysts. Crucially, comprehensive mechanistic analysis reveals a synergistic dual-activation of catalyst. For MOR, the optimized Ni2+/Ni3+ redox couple and stabilized Mn3+ species promote rapid methanol adsorption and C-H bond cleavage. For OER, embedded Ni electronically triggers the Adsorbate Evolution Mechanism (AEM) and facilitates Ni-induced oxygen vacancies, activating the low-overpotential Lattice Oxygen Mediated (LOM) pathway, evidenced by a low Tafel slope of 88.94 mV.dec−1. This work establishes a fundamental and practical structure-activity blueprint for next-generation, non-precious-metal electrocatalysts for advanced, environmentally beneficial energy conversion technologies.
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    Thiourea modulated supercapacitive behavior of reduced graphene oxide
    (Elsevier, 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.