Anion exchange membrane (AEM) water electrolysis can afford cheaper hydrogen (H₂) production compared to the current state-of-the-art of proton exchange membrane (PEM) electrolysis. In AEM electrolysis, i.e., in alkaline environment, platinum group metal (PGM)-free catalysts can be adopted as oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalysts, contrary to the PEM electrolysis in which PGM-catalysts should be used. Furthermore, expensive titanium flow-field that is indispensable in acidic PEM electrolyzer can be replaced by inexpensive stainless flow-field. These advantages of AEM electrolysis make AEM electrolysis attractive technology to produce H₂ in low cost. However currently performance of AEM electrolysis is much lower than that of PEM electrolysis. Therefore to make the AEM electrolysis technology viable, significant advancement in AEM electrolysis technology is needed.

Many PGM-free OER catalysts measured in aqueous alkaline electrolytes, such as 0.1 M KOH or NaOH, have demonstrated as high activities as that of PGM IrO₂ OER catalysts measured in an aqueous acid electrolytes in an electrochemical cell test. This implies that the low AEM electrolysis performance is possibly caused by some detrimental effect of AEM/anion exchange ionomer (AEI) onto catalysts. In this work we exploited different types of catalysts and AEIs to investigate the effect of catalyst-AEI interaction on AEM electrolysis performance. We observed that catalyst-AEI interaction substantially affects the AEM water electrolysis performance. The higher activity and durability of perovskite oxide OER catalyst than IrO₂ OER catalyst in AEM water electrolysis can be explained by this catalyst-AEI interaction.

In this talk, we will discuss the causes for low AEM electrolysis and possible pathways to improve AEM water electrolysis performance.

Acknowledgements

The authors gratefully acknowledge research support from the HydroGEN Advanced Water Splitting Materials Consortium, established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office.