Insight into the hydrogen oxidation electrocatalytic performance enhancement on Ni via oxophilic regulation of MoO₂

Exploring platinum-group-metal (PGM) free electrocatalysts for hydrogen oxidation reaction (HOR) in alkaline media is essential to the progress of anion exchange membrane fuel cells (AEMFCs). In this work, a Ni/MoO₂ heterostructure catalyst with comparable HOR activity in alkaline electrolyte with PGM catalyst was prepared by a simple hydrothermal-reduction method. Remarkably, the Ni/MoO₂ presents a mass kinetic current density of 38.5 mA mg_Ni⁻¹ at the overpotential of 50 mV, which is higher than that of the best PGM free HOR catalyst reported by far. Moreover, the HOR performance of Ni/MoO₂ under 100 ppm CO shows negligible fading, together with the superior durability, render it significant potential for application in AEMFCs. A particular mechanistic study indicates that the excellent HOR performance is ascribed to the accelerated Volmer step by the incorporation of MoO₂. The function of MoO₂ was further confirmed by CO striping experiment on Pt/C-MoO₂ that MoO₂ can facilitated OH adsorption thus accelerate the HOR process. On account of the high performance and low cost, the Ni/MoO₂ electrocatalyst encourages the establishment of high performance PGM free catalyst and shows significant potential for application in AEMFCs.