Seawater Electrolysis Using All-PGM-Free Catalysts and Cell Components in an Asymmetric Feed

High Resolution Image Download MS PowerPoint Slide In arid coastal zones, direct seawater electrolysis appears particularly intriguing for green hydrogen production. State-of-the-art direct seawater electrolyzers, however, show unsatisfactory performance and rely on large amounts of platinum-group metals (PGMs) in the electrodes or hidden as transport layer coatings. Herein, we report an asymmetric-feed electrolyzer design, in which all cell components consist of PGM-free materials. Cobalt- and nickel-based phosphides/chalcogenides not only serve as active and robust electrocatalysts but also are put forth as porous transport layer (PTL) surface coatings enhancing selective seawater splitting performance. In a systematic design study at the single-cell level, we report the integration of our catalysts and PTLs into a membrane–electrode assembly (MEA) using a customized, terphenyl-based anion-exchange membrane (AEM). The presented entirely PGM-free electrolyzer achieves industrially relevant current densities of up to 1.0 A cm –2 below 2.0 V cell in standardized alkaline seawater and dry cathode operation.