Crystalline-Amorphous Interface Coupling of Ni₃S₂/NiP _x/NF with Enhanced Activity and Stability for Electrocatalytic Oxygen Evolution

The rational design of highly efficient and stable electrocatalysts for the oxygen evolution reaction (OER) is an urgent need but remains challenging for various sustainable energy systems. How to adjust the atomic structure and electronic structure of the active center is a key bottleneck problem. Accelerating the electron transfer process and the deep self-reconstruction of active sites could be a cost-effective strategy toward electrocatalytic OER catalyst development. Here, a crystalline-amorphous (c-a) coupled Ni₃S₂/NiP_x electrocatalyst self-supported on nickel foam with an intimate interface was developed via a feasible solvothermal-electrochemistry method. The coupling interface of the crystalline structure with high conductivity and amorphous structure with numerous potential active sites could regulate the electronic structure and optimize the adsorption/desorption of O-containing species, ultimately resulting in high OER catalytic performance. The obtained Ni₃S₂/NiP_x/NF presents a low OER overpotential of 265 mV to obtain 10 mA·cm^-2 and a small Tafel slope of 51.6 mV·dec^-1. Also, the catalyst with the coupled interface exhibited significantly enhanced long-term stability compared to the other two catalysts, with <5% decay in OER activity over 20 h of continuous operation, while that of Ni₃S₂/NF and NiP_x/NF decreased by about 30 and 50%, respectively. This study provides inspiration for other energy conversion reactions in optimizing the performance of catalysts by coupling crystalline-amorphous structures.