Enabling low-IrO2 proton exchange membrane water electrolysis via microporous layer-supported catalyst-coated membranes

The effective utilization of IrO2 nanoparticles, employed as the anode catalyst for proton exchange membrane water electrolysis (PEMWE), is compromised at low loadings (≤0.1 mg cm−2) due to poor in-plane electronic conductivity. Herein, we demonstrate a microporous layer (MPL)-supported catalyst-coated membrane (CCM) where a low-loaded IrO2 catalyst layer is supported with 0.4 mg cm−2 Pt black in a bilayer configuration. The MPL-supported CCM configuration is shown to significantly enhance the kinetics, mass transport, and conductivity of low-loaded IrO2 anodes, achieving performance parity with high-loaded (1 mg cm−2) IrO2 anodes for PEMWE. Stability testing indicates that oxidation of the anode flow plate is the primary source of anode instability. MPL material transfer onto the anode porous transport layer during stability testing precludes reusability of the MPL-supported CCMs, which requires further investigation.