Facile synthesis of electrocatalytically active NbS2 nanoflakes for an enhanced hydrogen evolution reaction (HER)

We report a simple ambient pressure annealing technique for the synthesis of ultrathin niobium disulfide (NbS2) nanoflakes. The structure, morphology and composition of the as-synthesized NbS2 flakes are well characterized using various microscopic and spectroscopic techniques. The synthesized two-dimensional layered NbS2 is in stoichiometric proportion, and has a single crystal 3R-NbS2 polymorph structure with semiconducting behavior and has abundant catalytic defect sites. In this paper, the hydrogen evolution reaction (HER) activity of the NbS2 nanoflakes/rGO composite having dense exposed basal planes with improved conductivity is explored, and it is found to be a good HER catalyst in terms of low onset potential, low Tafel slope and high exchange current density.