Strain‐Induced Dynamic Surface Exchange in Ternary Alloy Nanosponges for Stable PEM Water Electrolysis

ABSTRACT The anodic oxygen evolution reaction (OER) in proton exchange membrane water electrolysis (PEMWE) struggles against a persistent trilemma: achieving low iridium loading without sacrificing activity or stability. To overcome this, we design ultrafine IrRuCu ternary alloy nanosponges featuring an “artery‐capillary” hierarchical mass‐transfer network, synthesized via surfactant‐assisted ethylene glycol reduction and selective etching. This catalyst exhibits a distinct gradient core‐shell architecture, where lattice mismatch from the Cu/Ru‐rich core triggers significant tensile strain in the outer active Ir shell. Integrating a series of comprehensive in situ characterization and DFT calculations, we uncover a novel, non‐destructive strain‐induced dynamic surface exchange mechanism. Tensile strain upshifts the Ir d ‐band center from −2.3 to −1.7 eV, amplifying the covalency and electrophilicity of surface Ir‐O bonds to assemble a dense hydroxyl network at open‐circuit potential. This geometric‐electronic modulation slashes the rate‐determining * O to * OOH barrier. Active surface oxygen directly accelerates kinetics, while rapid water refilling prevents bulk dissolution. Consequently, the alloy nanosponges require a 220 mV overpotential at 10 mA cm −2 , boasting a mass‐specific activity 59.2 times that of commercial benchmarks. Demonstrating over 4500 h of stability in industrial‐scale PEMWE full‐cells, this paradigm offers a compelling route toward economical green hydrogen.