Abstract
‘Green hydrogen’ can be one of the promising energy technologies in near future. Therefore, the importance of discovering the efficient electrocatalysts for hydrogen generation can never be refuted. The present work demonstrates a facile, ultrafast (60 s) microwave-assisted synthesis approach to develop an electrocatalyst of molybdenum sulfotelluride on graphene support, which is denoted as MoSxTey/Gr. The abundant interfaces in hybrid nanostructure of MoSxTey/Gr enable more exposed active sites for electrochemical reaction, facilitating the ion and charge transport activities. Among the resultant nanocomposites with different elemental ratios of Mo, S and Te, the MoS0.46Te0.58/Gr exhibits the best hydrogen evolution property with a low overpotential of 62.2 mV at 10 mA cm−2, a small Tafel slope of 61.1 mV dec−1, and long–term stability in 0.5 M H2SO4 electrolyte. Moreover, the tool of periodic plane-wave density functional theory (DFT) has been used to elucidate hydrogen binding energetics on various molybdenum sulfotelluride (stoichiometric and non-stoichiometric molybdenum-rich) on graphene nanocomposite systems. According to the computational results, high-performing catalytically active sites are found to be comprised of primarily exposed Mo atoms, thus showing Mo enrichment as a potential method for electrocatalyst engineering. Furthermore, in a volcano plot constructed with both computational and experimental values, the position of the MoS0.46Te0.58/Gr nanocomposite is found to be close to the apex with near thermoneutral catalytic activity.
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•Synthesis of novel nanocomposites of molybdenum sulfotelluride on graphene support.•Optimization of reaction conditions for microwave-assisted heating method.•Excellent electrocatalytic activities of MoS0.46Te0.58/Gr for hydrogen generation.•Near thermoneutral catalytic activity of MoS0.46Te0.58/Gr from DFT study.•High-performing catalytically active sites comprised of primarily exposed Mo atoms.