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

In arid coastal zones, direct seawater electrolysis appears particularly intriguing for green hydrogen production. Stateof-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 nickelbased 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.

Automated summary

This study presents an asymmetric-feed electrolyzer design that uses PGM-free materials and achieves high current densities for seawater electrolysis in alkaline conditions.