Ni–Mo nitride synthesized via mild plasma for efficient alkaline hydrogen evolution electrocatalysis

Abstract

Transition metal nitrides (TMNs) show intriguing electrocatalytic activity toward the hydrogen evolution reaction (HER), yet their synthesis generally involves high temperature pyrolysis with hazardous emission. Herein, a mild surface nitridation strategy was designed to synthesize Ni–Mo bimetallic nitride from a bimetal oxide precursor for HER electrocatalysis in alkaline solution. A heterostructured Ni₃N/Mo₂N polycrystalline layer was formed on Ni–Mo oxide nanorod tethered Ni foam (NMN/NF) upon near-room temperature H₂/N₂ mixed plasma treatment of the Ni–Mo oxide hydrate nanorod precursor (NMO/NF). The as-synthesized NMN/NF catalyst requires an ultra-low overpotential of 66 mV to deliver 100 mA cm⁻² current density in alkaline media, exhibiting better HER activity than benchmark Pt/C and Ni₄Mo alloy catalysts. Theoretical calculation disclosed that the excellent HER performance is attributed to the synergistic effect of Mo₂N and Ni₃N to promote water dissociation and H adsorption, respectively.