• ASHOK K GANGULI

      Articles written in Bulletin of Materials Science

    • Ternary alloy nanocatalysts for hydrogen evolution reaction

      SOUMEN SAHA SONALIKA VAIDYA KANDALAM V RAMANUJACHARY SAMUEL E LOFLAND ASHOK K GANGULI

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      Cu–Fe–Ni ternary alloys (size ∼55–80 nm) with varying compositions viz. CuFeNi (A1), CuFe2Ni (A2) and CuFeNi2 (A3) were successfully synthesized using microemulsion. It is to be noted that synthesis of nanocrystallineternary alloys with precise composition is a big challenge which can be overcome by choosing an appropriate microemulsion system. High electrocatalytic activity towards HER in alkaline medium was achieved by the formation of alloys of metals with low and high binding energies. A high value of current density (228 mA cm$^2$) at an overpotential of 545 mV was obtained for CuFeNi (A1), which is significantly high as compared to the previously reported Ni$_{59}$Cu$_{41}$ alloy catalyst.

    • Synthesis of Chevrel phase (Cu$_{1.8}$Mo$_6$S$_8$) in composite with molybdenum carbide for hydrogen evolution reactions

      KASINATH OJHA SHIVALI BANERJEE MANU SHARMA PREETI DAGAR ASHOK K GANGULI

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      Sustainable hydrogen generation from water electrolysis using renewable energy sources is the most promising pathway for future energy and hydrogen economy. Here, the Chevrel phase (Cu$_{1.8}$Mo$_6$S$_8$) was synthesized in composite with Mo$_2$C and good hydrogen evolution activity in acidic media has been demonstrated. Bundles of nanowires were formed in the templated synthesis route. The composites were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and elemental analysis. Detailed electrochemical analysis reveals that MCS-Cu50 compositeexhibits higher hydrogen evolution reaction (HER) activity with 71.4 mA cm$^{−2}$ current density at an overpotential of 400 mV. It requires 250 mV overpotential to produce 10 mA cm$^{−2}$ current density for HER.

    • Enhanced hydrogen evolution reactivity on Mo$_2$C–Mo$_2$N composites

      DEBDIPTO ACHARYA KASINATH OJHA NISHA MAMMEN PREETI DAGAR SOURAV MONDAL ASHOK K GANGULI SHOBHANA NARASIMHAN

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      We have studied the electrolysis of water, by performing a combined experimental and theoretical study of the hydrogen evolution reaction (HER) capability of Mo$_2$C–Mo$_2$N composites. Experimentally, we have synthesized nanowires with varying Mo$_2$C:Mo$_2$N ratios. We have found that the composites show good HER activity in an acidic medium, that is superior to that of either pristine Mo$_2$C or Mo$_2$N. These experimental results are supported by ab initio density functional theory calculations. Interestingly, we find that it is vital to incorporate van der Waals corrections toaccurately reproduce the experimentally observed structural transition from an orthorhombic to tetragonal phase as $x$, the N concentration in Mo$_2$C$_{1-x}$N$_x$, is increased. By computing Gibbs free energy for H adsorption on Mo$_2$C$_{1-x}$N$_x$ surfaces, our calculations confirm the experimental finding that mixed systems have superior HER activity to pristine systems, withN-rich systems being most active.

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