Atomically Dispersed IrMo Nanoclusters Anchored on N‐Doped Hollow Carbon Nanospheres for Enhanced Alkaline Hydrogen Oxidation Reaction

The slow hydrogen oxidation reaction (HOR) rate at the anode of the anion exchange membrane fuel cell currently holds back its further development. In this study, N-doped porous hollow carbon spheres (NHCSs) as a support are created, and highly dispersed small-sized IrMo nanoclusters (3.05 nm NCs) as the active species within NHCSs. The Ir₁Mo₅/NHCS composite exhibits excellent HOR catalytic activity in 0.1 M KOH solution with a mass activity of 2687.20 mA mg^-1 and an exchange current density of 11.0 mA cm^-2, which are 6.7 and 7.9 times higher than those of commercial Pt/C, respectively. Experiments and theoretical calculations suggest that Ir and Mo act as dual active sites for the H* and OH* adsorption. The high HOR catalytic activity of Ir₁Mo₅/NHCSs is attributed to the synergistic effect of Ir and Mo, which modulates the d-band center of the catalyst and thus optimizes the binding energy of H* and OH*. Furthermore, the spatial confinement effect of the highly porous support structure, combined with the anchoring effect of N doping, not only increases the dispersion and exposure of active IrMo NCs, but also enhances their structural stability and resistance to CO poisoning.