Electrochemical tuning of a CuP/NiP hybrid for a promoted hydrogen evolution reaction.

Developing novel and high performance electrocatalysts for use in hydrogen evolution reactions (HER) as substitutes for noble metal based electrocatalysts is imperative and, so far, has been a challenge. Herein, a self-supported CuP/NiP hybrid on nickel foam (CuP/NiP@NF) is prepared by a simple galvanic replacement reaction coupled with phosphorization. Subsequently, CuP/NiP@NF is modified by conducting cyclic voltammetry scans in 0.5 M HSO solution. Interestingly, after electrochemical tuning, the as-prepared CuP/NiP@NF exhibits significantly enhanced HER activity. Particularly, the resultant CuP/NiP@NF catalyst after 4000 cycles exhibits superior catalytic activity and long-term stability for HER with an overpotential of only 67 mV at the current density of 10 mA cm, and a low Tafel slope of 43.9 mV dec. The improved HER performance is attributed to the increased intrinsic activity of the CuP/NiP@NF with its optimized crystal and electronic structure, as well as an increased number of accessible active sites due to surface dissolution and recrystallization induced by electrochemical modification.