Amorphous MoO_x with High Oxophilicity Interfaced with PtMo Alloy Nanoparticles Boosts Anti‐CO Hydrogen Electrocatalysis

Abstract Advancing electrocatalysts for alkaline hydrogen oxidation/evolution reaction (HOR/HER) is essential for anion exchange membrane‐based devices. The state‐of‐the‐art Pt‐based electrocatalysts for alkaline HOR suffer from low intrinsic activities and severe CO poisoning due to the challenge of simultaneously optimizing surface adsorption toward different adsorbates. Herein, this challenge is overcome by tuning an atomic MoO_x layer with high oxophilicity onto PtMo nanoparticles (NPs) with optimized H_ad, OH_ad, and CO_ad adsorption for boosting anti‐CO‐poisoning hydrogen‐cycle electrocatalysis in alkaline media. For alkaline HOR, this catalyst exhibits high kinetics and an exchange current density of 3.19 mA µg_Pt⁻¹ at 50 mV versus reversible hydrogen electrode and 0.83 mA cm_Pt⁻², 10.3‐ and 3.8‐fold higher than those of commercial Pt/C, respectively. For alkaline HER, it achieves an unprecedented overpotential of 37 mV at 10 mA cm⁻². Experimental and theoretical studies show that the orchestrated electronic and oxophilic regulation of the PtMo/MoO_x interface NPs simultaneously optimizes H_ad and OH_ad adsorption for boosting alkaline hydrogen electrocatalysis, whereas reactive oxygen from the amorphous MoO_x atomic layer lowers the CO oxidation reaction barrier, leading to superior anti‐poisoning ability even at 100 ppm CO.