Potential-Dependent Stability of Iridium–Cobalt Oxide Nanosheets for Proton Exchange Membrane Water Electrolysis
Iridium-doped cobalt oxide nanosheets derived from a ZIF template were evaluated as oxygen evolution reaction (OER) catalysts for proton exchange membrane water electrolysis (PEMWE). Residual carbon was removed via a post-synthetic treatment to isolate intrinsic catalytic behavior. The Ir0.23Co0.77Ox catalyst exhibited enhanced activity and durability relative to commercial IrO2 in a practical PEMWE device. Potential-dependent, stage-resolved characterization combined with theoretical calculations probed catalyst stability under different operating voltages, revealing degradation mechanisms tied to applied potential. Contact angle measurements showed that the Ir0.23Co0.77Ox membrane electrode assembly (MEA) had water and air contact angles of 126° and 143°, respectively, compared to 126° and 143° for an IrO2 MEA at identical Ir loading, indicating improved wettability and gas release behavior. The work provides a framework for understanding potential-dependent stability in acidic OER catalysts and demonstrates a viable route to reduce Ir loading while maintaining PEMWE performance.