Cluster‐Scale Multisite Interface Reinforces Ruthenium‐Based Anode Catalysts for Alkaline Anion Exchange Membrane Fuel Cells

Ruthenium (Ru) is a more cost-effective alternative to platinum anode catalysts for alkaline anion-exchange membrane fuel cells (AEMFCs), but suffers from severe competitive adsorption of hydrogen (H_ad) and hydroxyl (OH_ad). To address this concern, a strongly coupled multisite electrocatalyst with highly active cluster-scale ruthenium-tungsten oxide (Ru-WO_x) interface, which could eliminate the competitive adsorption phenomenon and achieve high coverage of OH_ad and H_ad at Ru and WO_x domains, respectively, is designed. The experimental and theoretical results demonstrate that WO_x domain functions as a proton sponge to perpetually accommodate the activated hydrogen species that spillover from the adjacent Ru domain, and the resulting WO-H_ad species are readily coupled with Ru-OH_ad at the heterointerface to finish the hydrogen oxidation reaction with faster kinetics via the thermodynamically favorable Tafel-Volmer mechanism. The AEMFC delivers a high peak power density of 1.36 W cm^-2 with a low anode catalyst loading of 0.05 mg_Ru cm^-2 and outstanding durability (negligible voltage decay over 80-h operation at 500 mA cm^-2). This work offers completely new insights into understanding the alkaline HOR mechanism and designing advanced anode catalysts for AEMFCs.