Interfacial M–O–P coupling drives active-site reconfiguration in CoMoO4 for high-current-density alkaline hydrogen evolution

Abstract

Developing durable alkaline hydrogen evolution reaction (HER) cathodes capable of sustained operation at industrial current densities is critical for practical anion exchange membrane water electrolysis (AEMWE). Herein, phosphorus-modified CoMoO 4 nanoarrays (CoMoO 4 -P) are constructed to regulate the electronic communication between Co and Mo centers. Phosphorus incorporation generates interfacial M–O–P linkages (M = Co, Mo), strengthening Co–Mo electronic coupling and establishing cooperative catalytic sites. These cooperative Mo–Co sites promote interfacial charge redistribution and enable hydrogen adsorption to evolve from a mainly Mo-centered configuration to a delocalized Co–Mo interfacial mode, thereby accelerating alkaline HER kinetics. As a result, CoMoO 4 -P delivers 1000 mA cm −2 at overpotentials of 284 mV in alkaline freshwater and 338 mV in seawater, respectively, with stable operation over 500 h. When used as the cathode in an anion-exchange membrane water electrolyzer paired with RuO 2 , the CoMoO 4 -P||RuO 2 electrolyzer achieves 10 A cm −2 with a cell voltage of 3.27 V at 60 °C. This work highlights interfacial M–O–P coupling as an effective strategy for developing durable HER cathodes for high-current-density alkaline water electrolysis.