CoP@Ni core-shell heterostructure nanowire array: A highly efficient electrocatalyst for hydrogen evolution.

The inferior performance of non-precious metals on electrocatalytic hydrogen evolution can be mainly attributed to the inappropriate adsorption strength of intermediates. A core-shell heterostructure of CoP@Ni is developed by hydrothermal reaction, thermal phosphorization and subsequent electrodeposition, with metallic Ni supported by CoP nanowire array. The as-prepared CoP@Ni core-shell heterostructure nanowire array has a superior activity on hydrogen evolution in alkaline electrolyte, with an overpotential of 71 mV to drive 10 mA cm and a Tafel slope of 66 mV dec. The electronic structure of CoP@Ni is tuned for modulating the adsorption strength of intermediates. The theoretical calculations reveal that CoP@Ni has metallic characteristics with a zero-bandgap, which leads to the promoted charge transfer. More importantly, the intrinsic activity of CoP@Ni is greatly increased, with a lower energy barrier in the reaction pathway. This work points out the importance of constructing the heterostructure for improving the intrinsic activity, which can pave the way to the exploration of high-performance and cost-effective electrocatalysts for hydrogen production.