Benchmarking Stability of IrOx in Acidic Media under O2 Evolution Conditions: A Review

State-of-the-art proton exchange membrane (PEM) electrolysers employ iridium-based catalysts to facilitate oxygen evolution at the anode. To enable scale-up of the technology to the terawatt level, further improvements in the iridium utilisation are needed, without incurring additional overpotential losses or reducing the device lifetime. The research community has only recently started to attempt systematic benchmarking of catalyst stability. Short term electrochemical methods alone are insufficient to predict catalyst degradation; they can both underestimate and overestimate catalyst durability. Complementary techniques, such as inductively coupled plasma - mass spectrometry, are required to provide more reliable assessment of the amount of catalyst lost through dissolution. Herein, we critically review the state of the art in probing degradation of iridium-based oxide catalysts. We also highlight considerations and best practices for the investigation of activity and stability of oxygen evolution catalysts via short term testing.