DOI: 10.1002/advs.202401702 ISSN: 2198-3844

A Dual‐Cation Exchange Membrane Electrolyzer for Continuous H2 Production from Seawater

Yongwen Ren, Faying Fan, Yaojian Zhang, Lin Chen, Zhe Wang, Jiedong Li, Jingwen Zhao, Bo Tang, Guanglei Cui
  • General Physics and Astronomy
  • General Engineering
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • General Materials Science
  • General Chemical Engineering
  • Medicine (miscellaneous)

Abstract

Direct seawater splitting (DSS) offers an aspirational route toward green hydrogen (H2) production but remains challenging when operating in a practically continuous manner, mainly due to the difficulty in establishing the water supply–consumption balance under the interference from impurity ions. A DSS system is reported for continuous ampere‐level H2 production by coupling a dual‐cation exchange membrane (CEM) three‐compartment architecture with a circulatory electrolyte design. Monovalent‐selective CEMs decouple the transmembrane water migration from interferences of Mg2+, Ca2+, and Cl ions while maintaining ionic neutrality during electrolysis; the self‐loop concentrated alkaline electrolyte ensures the constant gradient of water chemical potential, allowing a specific water supply–consumption balance relationship in a seawater–electrolyte–H2 sequence to be built among an expanded current range. Even paired with commercialized Ni foams, this electrolyzer (model size: 2 × 2 cm2) continuously produces H2 from flowing seawater with a rate of 7.5 mL min−1 at an industrially relevant current of 1.0 A over 100 h. More importantly, the energy consumption can be further reduced by coupling more efficient NiMo/NiFe foams (≈6.2 kWh Nm−3 H2 at 1.0 A), demonstrating the potential to further optimize the continuous DSS electrolyzer for practical applications.

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