High-Performance Non-Precious Metal Cathode for Pure-Water Hydroxide Exchange Membrane Electrolyzers

The advancement of hydroxide exchange membrane electrolyzers (HEMEL) holds promise for reducing the cost of green hydrogen production. Despite noticeable progress in designing highly active non-precious metal electrocatalysts, their performance has been largely demonstrated in three-electrode based liquid cell testing and is difficult to translate into membrane-based electrolyzer devices. The key reason is the suboptimal electrode architecture limits effective catalyst utilization in devices. In this study, we propose a general approach to optimizing catalyst layer structure and interfaces for effective cathode development. The pure-water-fed HEMEL equipped with non-precious metal catalysts (NiFeOOH anode and NiMo cathode) demonstrates an impressive performance with a current density of 520 mA cm −2 at 1.8 V and stable operation at 1000 mA cm −2 for over 68 h. Our findings underscore the critical role of a rationally designed electrode structure in achieving high activity and durability in pure-water-fed HEMEL. The proposed design strategies may also guide electrode development for other electrochemical energy devices.