Two-Dimensional CoS_x/SnS_x Chalcogenides Layered Ultrathin Nanosheets for Electrocatalytic Hydrogen Evolution

Hydrogen evolution reaction (HER) via water splitting through electrocatalysis using advanced inexpensive materials to replace precious platinum catalysts holds great promise for clean energy technology. Ultrathin two-dimensional nanosheets of layered transition metal chalcogenides are fundamentally and technologically intriguing. Mono- or few- layered chalcogenides obtained either through exfoliation of bulk materials or bottom-up synthesis are depending on their composition, structure, and dimensionality. Herein, we designed an intra-layered CoSx/SnSx catalysts with abundant exposed edges anchored on reduced graphene oxide through facile hydrothermal process. The intra-layers play a crucial role in tuning their intrinsic catalytic properties and long-term stability by creating substantial intrinsic active sites and covalent nature of inter-layer. The CoSx/SnSx catalyst exhibited a large cathodic current, low overpotential of 37 mV at 10 mA cm-2, small Tafel slope of 62 mV dec-1, and long-term stability in acidic environments than those of noble metals. This work shows a grate potential for scalable, low-cost, and highly efficient catalysts for hydrogen evolution, fuel cells.