Mitigating Hydrogen-Induced Degradation of Iridium Anodes in Proton Exchange Membrane Water Electrolyzers

One promising method for reducing precious metal usage in proton exchange membrane water electrolysis is lowering iridium (Ir) loading at the anode. However, low-loading Ir catalysts often suffer from poor stability under high current densities. In this study, hydrogen (H 2 ) crossover from the cathode to the anode is identified as a key degradation pathway. Temperature-programmed reduction confirms the reduction of IrO 2 at 80 °C in a hydrogen environment, highlighting the vulnerability of IrO 2 -based catalysts to H 2 exposure. To mitigate this effect, palladium (Pd) is introduced as an anode additive, acting as an H 2 oxidation catalyst and mitigating IrO 2 reduction. This protective role is verified by inductively coupled plasma optical emission spectroscopy and in situ X-ray absorption spectroscopy, showing significantly suppressed Ir dissolution at 80 °C under H 2 flow when an O-covered Pd surface is present at oxygen evolution reaction potentials. Results from the current study identify a new strategy in improving activity and durability of catalysts in electrolyzers.