Construction of wool-shaped heterostructure structure CoNi/NF-P electrocatalyst for efficient hydrogen evolution reaction

Constructing high-activity, cost-efficient and long-term stability electrocatalysts plays a key role in hydrogen evolution reaction (HER) via water electrolysis. Transition metal phosphides (TMPs) have caused concern due to their abundant active sites, unique physicochemical properties, and tunable constituent structures. Rational design of heterojunction electrocatalysts can effectively improve electrochemical activity by synergistic effect, electronic interaction and strain effect. Herein, inspired by the structural superiority of TMPs and hetero-structural catalysts, we prepared wool-shaped cobalt-nickel phosphide (CoNi/NF-P) in-situ grown on nickel foam (NF) applied to HER under the alkaline condition by hydrothermal and calcination. CoNi/NF-P exhibited a low overpotential of 111.3 mV at 10 mA cm-2, a small value of Tafel slope of 67.7 mV dec- 1 and sustained stability up to 30 h at about 20 mA cm-2 for HER. The density functional theory (DFT) calculation indicates that the bimetallic synergistic effect facilitates the HER reaction kinetics by inducing strong hydrophilicity and hydrogen adsorption-free energy close to 0. This work will further broaden the horizon for 2D TMPs and heterojunction electrocatalyst applications in the alkaline hydrogen evolution reaction.