BITS Faculty Publications

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Author: search.filters.author.Pande, SurojitSubject: search.filters.subject.Electrical properties

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    Doping of MoS2 by “Cu” and “V”: An Efficient Strategy for the Enhancement of Hydrogen Evolution Activity
    (ACS, 2021-04) Basu, Mrinmoyee; Pande, Surojit
    To replace Pt-based compounds in the electrocatalytic hydrogen evolution reaction (HER), MoS2 has already been established as an efficient catalyst. The electrocatalytic activity of MoS2 is further improved by tuning the morphology and the electronic structure through doping, which helps the band energy position to be modified. Presently, thin sheets of MoS2 (MoS2-TSs) are synthesized via a microwave technique. Thin sheets of MoS2 can outperform nanosheets of MoS2 in the HER. Further, the efficiency of the thin sheets is improved by doping with different metals like Cu, V, Zn, Mn, Fe, Sn, etc. “Cu”- and “V”-doped MoS2-TSs are highly efficient for the HER. At a fixed potential of −0.588 V vs RHE, Cu-doped MoS2 (Cu-MoS2-TS), V-doped MoS2 (V-MoS2-TS), and MoS2-TS can generate current densities of 327.46, 308.45, and 127.82 mA/cm2, respectively. The electrochemically active surface area increases nearly 7.7-fold and 2.5-fold for Cu-MoS2-TS and V-MoS2-TS than for MoS2-TS, respectively. Cu-MoS2-TS shows exceptionally high electrocatalytic stability up to 140 h in an acidic medium (0.5 M H2SO4). First-principles calculations using density functional theory (DFT) are performed, which are well matched with the experimental observations. DFT calculations dictate that after doping with “V” and “Cu” both valance band maxima and conduction band minima are uplifted, which indicates the higher hydrogen-ion-reducing ability of M-MoS2-TS (M = Cu, V) compared to bare MoS2-TS.
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    Ag2S/Ag Heterostructure: A Promising Electrocatalyst for the Hydrogen Evolution Reaction
    (ACS, 2017) Basu, Mrinmoyee; Pande, Surojit; Gangopadhyay, Subhashis
    Different metal chalcogenides, being a potential candidate for hydrogen evolution catalysts, have attracted enormous attention in the field of water splitting. In the present study, Ag2S/Ag is revealed as an efficient catalyst for hydrogen evolution. When a sacrificial template of the CuS nanostructure is used, Ag2S/Ag heterostructures are synthesized following a simple wet-chemical technique. Two different routes, wet chemical and hydrothermal, are followed to modulate the morphology of the CuS templates from flower ball to wirelike structures, which subsequently results in the formation of Ag2S nanostructure. Finally, the Ag layer is deposited on Ag2S with the help of a photoreduction technique. The unique heterostructure of Ag2S/Ag shows efficient catalytic activity in the H2 evolution reaction. A Ag2S/Ag wire can successfully generate a 10 mA/cm2 current density at a −0.199 V potential. Ag2S/Ag contains the micronanostructure where nanoplates of Ag2S/Ag assemble to give rise to microstructures such as flower balls and wire.