Multi-interfacial engineering of a coil-like NiS-Ni2P/Ni hybrid to efficiently boost electrocatalytic hydrogen generation in alkaline and neutral electrolyte

Developing highly efficient and low-cost electrocatalysts for the hydrogen evolution reaction (HER) in alkaline and neutral media is crucial but still a significant challenge due to the sluggish multi-step reaction kinetics involved. The interface formed between two or more components in heterogeneous catalysts plays a critical role for electrocatalysis as it can tune the electron structure to enhance the catalytic performance. Herein, we report that multi-interface engineering of NiS, Ni2P and Ni on Ni foam results in a unique coil-like NiS-Ni2P/Ni hybrid electrocatalyst on Ni foam, which is synthesized through a two-step approach: firstly, electrodeposition of Ni microspheres on Ni foam (NF), followed by partial thermal sulfuration and phosphorization. Owing to the interfaces between NiS, Ni2P and Ni, which function as electrochemical active sites and are beneficial for dissociative adsorption of water molecules, the resultant NiS-Ni2P/Ni/NF exhibits much superior hydrogen evolution reaction (HER) catalytic activity with small overpotentials of 53 mV and 115 mV to deliver a current density of 10 mA cm(-2) in alkaline and neutral media. Remarkably, NiS-Ni2P/Ni/NF needs a lower overpotential than Pt/C to achieve a higher current density of 100 mA cm(-2). Density functional theory calculations suggested that the real active sites are located at the multi-interface of NiS, Ni2P and Ni, contributing an outstanding electrocatalytic performance. This work not only reports a highly efficient coil-like multi-interfacial NiS-Ni2P/Ni hybrid electrocatalyst on Ni foam for hydrogen production, but also paves a new way for designing other highly efficient electrocatalysts.