Carbon supported IrM (M = Fe, Ni, Co) alloy nanoparticles for the catalysis of hydrogen oxidation in acidic and alkaline medium

We studied the alloying effect in Ir-based alloys on the catalysis of the hydrogen oxidation reaction (HOR) in both acidic and alkaline medium. IrFe, IrNi and IrCo alloy catalysts with nanoparticle size of <5 nm were obtained by our solvent-vaporization plus hydrogen reduction method. The second metal played an important role in tuning the crystal structure and surface electronic structure of the Ir-based alloy catalyst. Among the IrFe, IrCo and IrNi alloy catalysts, Ni induced a mid-sized contraction of the Ir lattice, and gave the best HOR activity in both acidic and alkaline medium. In acidic medium, the weakening of the Ir–Had interaction caused by the electronic effect of M (M = Fe, Ni, Co) alloying is responsible for the enhancement of HOR activity. The oxophilic effect of the catalytic metal surface, which affects OHad adsorption and desorption and surface Had coverage, has a large impact on the HOR activity in the case of alkaline medium.