Atomically dispersed Iridium on Mo 2 C 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 Mo 2 C nanoparticles supported on carbon (Ir SA -Mo 2 C/C) as highly active and stable HOR catalysts. The specific exchange current density of Ir SA -Mo 2 C/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 Mo 2 C 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 -Mo 2 C/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.