Atomically dispersed Iridium on Mo2C as an efficient and stable alkaline hydrogen oxidation reaction catalyst

Hydroxide exchange membrane fuel cells (HEMFCs) have the advantages of using cost-effective materials, but hindered by the sluggish anodic hydrogen oxidation reaction (HOR) kinetics. Here, we report an atomically dispersed Ir on Mo₂C nanoparticles supported on carbon (Ir_SA-Mo₂C/C) as highly active and stable HOR catalysts. The specific exchange current density of Ir_SA-Mo₂C/C is 4.1 mA cm^-2_ECSA, which is 10 times that of Ir/C. Negligible decay is observed after 30,000-cycle accelerated stability test. Theoretical calculations suggest the high HOR activity is attributed to the unique Mo₂C substrate, which makes the Ir sites with optimized H binding and also provides enhanced OH binding sites. By using a low loading (0.05 mg_Ir cm^-2) of Ir_SA-Mo₂C/C as anode, the fabricated HEMFC can deliver a high peak power density of 1.64 W cm^-2. This work illustrates that atomically dispersed precious metal on carbides may be a promising strategy for high performance HEMFCs.