Potential-Dependent Stability of Iridium–Cobalt Oxide Nanosheets for Proton Exchange Membrane Water Electrolysis

• • Ir0.23Co0.77Ox nanosheets achieved a water contact angle of 126° and air contact angle of 143°, versus 126° and 143° for commercial IrO2 at the same Ir loading, indicating superior liquid–gas transport within the catalyst layer and potential for reduced mass-transport overpotential at high current densities. • • The catalyst exhibited excellent activity and durability in a practical PEMWE device, with performance metrics surpassing commercial IrO2, addressing the critical need for low-Ir-loading catalysts in acidic OER. • • Potential-dependent, stage-resolved characterization identified voltage-specific degradation pathways, enabling rational design of operating windows to mitigate catalyst failure under dynamic PEMWE conditions. • • Removal of residual carbon from the ZIF-derived template eliminated confounding effects, isolating intrinsic Ir–Co oxide activity and providing a clear structure–activity relationship for future catalyst optimization.