Ru-doping modulated electronic structure of bimetallic phosphide toward efficient overall water splitting

Efficient water splitting electrocatalysts with low cost is essential for the development of sustainable hydrogen energy. Ni foam supported Ru-doped NiCoP nanowire arrays (Ru–NiCoP@NF) are synthesized via a hydrothermal reaction followed by low-temperature phosphorization. The as-obtained Ru–NiCoP@NF exhibits outstanding bifunctional catalytic activity, achieving 100 mA cm−2 at the overpotentials of 108 and 264 mV for HER and OER, respectively, with a tiny loading of Ru (≈61.8 μg cm−2). The electrolyzer assembled using Ru–NiCoP@NF as the bifunctional electrode requires 1.62 V (with no iR correction) for 50 mA cm−2, 50 mV lower than RuO2–Pt/C based electrolyzer. The enhancement of Ru–NiCoP@NF is ascribed to Ru dopants, which contribute to formation of 3D nanowire arrays with the advantages of exposing sufficient active sites, accelerating charge transfer and outstanding mechanical strength. More importantly, the Ru atoms in NiCoP successfully modulate the charge densities around Ni, Co and P through strong electronic interaction, thus elevating the sluggish Volmer step for HER and promoting the adsorption capacity of oxygen-containing intermediates for OER.