Constructing three-dimensional porous Ni/NiS nano-interfaces for hydrogen evolution electrocatalysis under alkaline conditions.

It is still a challenging issue to design earth-abundant electrocatalysts with low cost, high activity and long-term stability for the hydrogen evolution reaction (HER) based on water splitting in alkaline solutions. Here, we report a facile synthetic route for a three-dimensional, porous Ni/NiS nano-network on carbon cloth for the efficient catalysis of HER. This unique structure exposes a high proportion of Ni/NiS hetero-interfaces to the electrolyte, creating a synergetic effect between Ni and NiS that enhances HER. The synergetic effect at the interface was verified by DFT calculation and involves the interface-assisted heterolytic splitting of HO into OH and H and the subsequent expeditious H-forming reaction caused by weakened binding between Ni and H induced by the neighboring NiS. The resulting porous network shows high HER activity in alkaline media, reaching 10 mA cm at 95 mV with a Tafel slope of 66 mV dec. This value is much smaller than that of nickel metal, which is currently used in industry.