High Performance Low PGM Alkaline Membrane Water Electrolysis

Development of water electrolysis technology is critical to the future of clean energy consumption and storage. Alkaline membrane water electrolysis is very attractive owing to the high energy density of the hydrogen produced and, more importantly, the possibility of lowering system cost by significantly lowering or completely replacing platinum group metal (PGM) catalysts with less expensive metals such as nickel and iron. Replacing perfluorinated membranes with much less expensive hydrocarbon based materials such as oxidation-resistant alkaline membranes and ionomer that are stable under water electrolysis operating conditions will also improve system costs and durability requirements. Previous research has focused on alkaline electrolyzers operating with KOH supporting electrolyte.1 To date, it is clear that alkaline membrane electrolysis is still low technology readiness leveltechnology with reported limitations such as membrane/ionomer durability, non-PGM catalyst performance and durability and previously mentioned, operation with a supporting electrolyte, such as KOH to achieve performance, which adds significant cost to design a corrosion resistant device. In this study, we have developed an alkaline membrane water electrolyzer which operates with pure water and employs non-PGM anode catalyst. Initial focus was to demonstrate membrane and ionomer performance and durability during electrolyzer operation without the use of added electrolyte. We have demonstrated for the first time 500 hours of cell operation with pure water at 500 mA/cm2 and a cell potential of 1.7 V using standard PGM catalysts indicating significant durability. Replacing the iridium oxide with PGM-free catalyst and operating the electrolyzer with pure water will lead to significant cost saving both in catalyst materials and allow for less expensive stainless-steel current collectors. More recently, an alkaline water electrolyzer with iron and nickle based PGM-free based anode catalysts has demonstrated promising performance while operating on pure water. Reference Abbasi, R., Setzler, B. P., Lin, S., Wang, J., Zhao, Y., Xu, H., Pivovar, B., Tian, B., Chen, X., Wu, G., Yan, Y., A Roadmap to Low‐Cost Hydrogen with Hydroxide Exchange Membrane Electrolyzers. Mater.2019, 31, 1805876