Advancing the Co-Based Anode Catalysts Using Ionomers in Pure-Water Anion Exchange Membrane Electrolyzers

Abstract

Anion exchange membrane electrolyzers can cost-effectively produce green hydrogen by utilizing earth-abundant catalysts and pure-water. However, their durability is limited by the degradation of the anode catalyst and ionomer under pure-water conditions. To develop effective strategies for enhancing durability, it is crucial to understand the mechanisms of anode degradation and evaluate the influence of ionomers on this process. In this study, the impact of ionomers is analyzed on the durability of Co-based anode catalysts and enhanced their durability. Under high-current-density operation, the Co-based catalyst undergoes surface reconstruction into agglomerates between stainless-steel fibers, which results in a decrease in the oxygen evolution performance. Notably, optimal ionomer coating enhances the performance during surface reconstruction. This effect is investigated through in situ electrochemical analyses and ex situ material characterizations, uncovering the performance and structural changes of the anode catalyst over time. The durability of the Co-based catalyst is further enhanced through electrochemical activation, thereby achieving a voltage change rate of ≈0.28 mV h−1 during 400 h of operation at 1 A cm−2.