Operation-induced reconstruction of self-supported nickel-tungsten-copper phosphides into hydroxide-metal working...

Industrial alkaline hydrogen evolution requires electrocatalysts that remain active and stable at high current densities, yet their working-state evolution throughout operation remains inadequately understood for further enhancement of performance. Here, we report a self-supported NiWCu phosphide electrode on nickel mesh (NiWCu-P/NM) that undergoes operation-induced reconstruction under alkaline hydrogen evolution reaction (HER) conditions. Post-reaction analyses support that phosphorus leaching leads to the formation of an amorphous Ni(OH)₂ overlayer and partial tungsten dissolution is accompanied by the formation of a NiCu metallic substrate. Oxidized W(VI)-containing species remain detectable on the washed electrode, while tungsten is also released into the electrolyte, suggesting a dynamic solution-surface environment responsible for the cathode activity and stability. The activated electrode requires an overpotential of 248 mV to reach 500 mA cm^-2 in 6 M NaOH at 30 °C and shows a 39 mV increase in overpotential after 100 h at 500 mA cm^-2. In a platinum-group-metal-free (PGM-free) anion-exchange membrane water electrolyzer (AEMWE) using NiFe-LDH/NM as the anode, the device delivers 0.5 and 2.0 A cm^-2 at cell voltages of 1.66 and 1.97 V, respectively, in 1 M KOH at 80 °C, and operates for 400 h at 0.5 A cm^-2. Density functional theory (DFT) calculations further indicate interfacial charge redistribution and more favorable hydrogen adsorption thermodynamics at the reconstructed interfaces. This work demonstrates that operation-induced reconstruction can be exploited to construct hydroxide/metal working interfaces for high-current alkaline hydrogen evolution.