Bias-Induced Ga−O-Ir Interface Breaks the Limits of Adsorption-Energy Scaling Relationships for High-Performing Proton Exchange Membrane Electrolyzers

Abstract

Rationally manipulating the in situ formed catalytically active surface of catalysts remains a significant challenge for achieving highly efficient water electrolysis. Herein, we present a bias-induced activation strategy to modulate in situ Ga leaching and trigger the dynamic surface restructuring of lamellar Ir@Ga₂O₃ for the electrochemical oxygen evolution reaction. The in situ reconstructed Ga−O−Ir interface sustains high water oxidation rates at oxygen evolution reaction (OER) overpotentials. We found that OER at the Ga−O−Ir interface follows a bi-nuclear adsorbate evolution mechanism with unsaturated IrO_x as the active sites, while GaO_x atoms play an indirect role in promoting water dissociation to form OH* and transferring OH* to Ir sites. This breaks the scaling relationship of the adsorption energies between OH* and OOH*, significantly lowering the energy barrier of the rate-limiting step and greatly increasing reactivity. The Ir@Ga₂O₃ catalyst achieves lower overpotentials, a current density of 2 A cm⁻² at 1.76 V, and stable operation up to 1 A cm⁻² in scalable proton exchange membrane water electrolyzer (PEMWE) at 1.63 V, maintaining stable operation at 1 A cm⁻² over 1000 hours with a degradation rate of 11.5 μV h⁻¹. This work prompted us to jointly address substrate–catalyst interactions and catalyst reconstruction, an underexplored path, to improve activity and stability in Ir PEMWE anodes.