Hydroxyapatite‐Derived Heterogeneous Ru‐Ru2P Electrocatalyst and Environmentally‐Friendly Membrane Electrode toward Efficient Alkaline Electrolyzer

Alkaline membrane water electrolysis is a promising production technology, and advanced electrocatalyst and membrane electrode design have always been the core technology. Herein, an ion-exchange method and an environmentally friendly in situ green phosphating strategy are successively employed to fabricate Ru-Ru2 P heterogeneous nanoparticles by using hydroxyapatite (HAP) as a phosphorus source, which is an exceptionally active electrocatalyst for hydrogen evolution reaction (HER). Density functional theory calculation results reveal that strong electronic redistribution occurs at the heterointerface of Ru-Ru2 P, which modulates the electronic structure to achieve an optimized hydrogen adsorption strength. The obtained Ru-Ru2 P possesses excellent HER performance (24 mV at 10 mA cm-2 ) and robust stability (1000 mA cm-2 for 120 h) in alkaline media. Furthermore, an environmentally friendly membrane electrode with a sandwich structure is assembled by HAP nanowires as an alkaline membrane, Ru-Ru2 P as a cathodic catalyst, and NiFe-LDH as an anodic catalyst, respectively. The voltage of (-) Ru-Ru2 P || NiFe-LDH/CNTs (+) (1.53 V at 10 mA cm-2 ) is lower than that of (-) 20 wt% Pt/C || RuO2 (+) (1.60 V at 10 mA cm-2 ) for overall water splitting. Overall, the studies not only design an efficient catalyst but also provide a new route to achieve a high-stability electrolyzer for industrial H2 production.