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.