Enhancing hydrogen evolution and oxidation kinetics through oxygen insertion into nickel lattice

Nickel-based materials, including metallic Ni and Ni oxide, have been widely studied in the exploration of non-precious-metal hydrogen electrocatalysts, but neither pure Ni nor NiO is ideal for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR). In this paper, an oxygen insertion strategy was applied on nickel to regulate its hydrogen electrocatalytic performance, and the oxygen-inserted nickel catalyst was successfully obtained with the assistance of tungsten dioxide support (denoted as O-Ni/WO2). The partial insertion of oxygen in Ni maintains the face-centered cubic arrangement of Ni atoms, simultaneously expanding the lattice and increasing the lattice spacing. Consequently, the adsorption strength of *H and *OH on Ni is optimized, thus resulting in superior electrocatalytic performance of O-Ni/WO2 in alkaline HER/HOR. The Tafel slope of O-Ni/WO2@NF for HER is 56 mV dec−1, and the kinetic current density of O-Ni/WO2 for HOR reaches 4.85 mA cm−2, which is ahead of most currently reported catalysts. Our proposed strategy of inserting an appropriate amount of anions into the metal lattice could provide more possibilities for the design of high-performance catalysts.