Surface Structure Evolution of Bimetallic Nickel Tungsten Nitride (Ni2W3N) for High Performance Hydrogen Evolution

Abstract

Bimetallic transition metal nitride (TMN)-based electrocatalysts have demonstrated potential for the hydrogen evolution reaction (HER) in alkaline electrolytes. However, simpler synthesis methods and a deeper understanding of the origin of their catalytic activity are needed. Here, we report a facile synthesis strategy for Ni2W3N on nickel foam (Ni2W3N/NF) using a one-step annealing method. The resulting Ni2W3N/NF exhibits excellent HER activity, with low overpotential values of 46.5 and 78.7 mV at current densities of 50 and 100 mAcm−2, respectively, and demonstrates high stability for 30 h. In-situ Raman spectroscopy revealed surface reconstruction during the HER process, characterized by tungsten dissolution and the formation of amorphous Ni(OH)2. Density functional theory calculations suggest that the Ni sites in amorphous Ni(OH)2 enhance water dissociation and optimize hydrogen binding energy, facilitating an efficient Volmer reaction, and thus improving hydrogen evolution.