Accelerating Alkaline Hydrogen Evolution via Interface‐To‐Surface Proton Transfer Relays on Ru‐RuO 2−δ Heterostructure

ABSTRACT Ru has been investigated as a promissing hydrogen evolution reaction (HER) catalyst in anion exchange membrane water electrolyzers (AEMWEs). However, its excessive oxophilicity blocks active sites and over‐structures interfacial water, limiting alkaline HER kinetics. In this work, we report a Ru‐RuO 2−δ heterostructure that overcomes these kinetic bottlenecks via an engineered interface‐to‐surface proton transfer relay. This architecture promotes a more flexible interfacial water network that facilitates Grotthuss‐type proton transport, coupled with facilitated hydrogen spillover from high‐affinity Ru clusters to low‐affinity RuO 2−δ surfaces. By decoupling proton delivery from surface binding, the Ru‐RuO 2−δ achieves an intrinsic activity 26‐fold higher than pristine Ru, requiring ultra‐low overpotentials of only 15 ± 4 and 165 ± 6 mV at 10 and 1000 mA cm −2 , respectively. Notably, the catalyst demonstrates long‐term durability under high‐current‐density operation (> 470 h at 1 A cm −2 ) with a degradation rate 2,000‐fold lower than commercial Pt/C. In a practical AEMWE, it delivers 1 A cm −2 at a cell voltage of 1.67 ± 0.02 V (45.1 ± 0.5 kWh kg H2 −1 ), meeting the U.S. DOE energy‐consumption target. Beyond providing a high‐performance alternative to platinum, this work introduces a design principle for accelerating electrocatalytic kinetics through the engineering of interface‐to‐surface transport relays.