A Ni-MoO_x composite catalyst for the hydrogen oxidation reaction in anion exchange membrane fuel cell

In developing anion exchange membrane fuel cells (AEMFCs), the sluggish hydrogen oxidation reaction (HOR) under alkaline condition is one of the major challenges to be overcome. A screening process using the simple electrodeposition method suggests Ni-29Mo as the most promising composition among the prepared Ni-M (M= Co, Fe, Zn, Cr, Mo, W) and Ni-xMo (x = 22∼33 at%) samples. Experimental analyses and theoretical computations demonstrate that the Ni-29Mo is composed of metallic nickel and molybdenum oxide (Ni-MoO_x) domains and the hydrogen adsorption energy on metallic Ni is tailored in the presence of MoO₂ towards the optimal value. The Ni-MoO_x composite catalyst shows a superior HOR activity (1.12 mA/cm² @ 20 mV_RHE), outperforming carbon supported platinum (Pt/C, 1.01 mA/cm² @ 20 mV_RHE), the best HOR catalyst. An AEMFC fabricated using Ni-29Mo nanoparticles as an anode catalyst exhibits excellent performance, approximately half of the Pt/C counterpart cell, demonstrating practical applicability of the catalyst.