Self-supported CuS nanowire array: an efficient hydrogen-evolving electrode in neutral media

A self-supported copper sulfide (CuS) nanowire array (NWA) of hierarchical and porous structure has been developed on Cu foil via two consecutive liquid-solid reactions at room temperature. The composition, structure and morphology of the as-prepared CuS NWA samples have been systematically investigated by a series of techniques. When applied as cathode for the hydrogen evolution reaction (HER) in neutral solution, the optimized CuS NWA electrode exhibits excellent HER performance with high long-term stability. To achieve current densities of 10 and 100   mA   cm −2 , it requires overpotentials of only ∼97 and ∼226   mV, respectively. The excellent catalytic performance of CuS NWA toward HER is attributable to the binder-free electrode construction strategy, the unique porous nanowire array structure, and the small solubility product ( K sp ) value of CuS that guarantees the high catalyst stability.