Fluorine-Induced Molybdate Trap-and-Buffer Enables Durable Intermittent Alkaline Seawater Electrolysis
Date
2025
Authors
Fu, D.
Sun, X.
Gao, F.Y.
Zheng, Y.
Qiao, S.Z.
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Journal article
Citation
Advanced Functional Materials, 2025; 36(31):e26332-1-e26332-8
Statement of Responsibility
Dengyu Fu, Xiaogang Sun, Fei-Yue Gao, Yao Zheng, and Shi-Zhang Qiao
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Abstract
Electrodes’ stability under intermittent operation remains a key bottleneck for alkaline seawater electrolysis. Especially, the cathode typically undergoes self-oxidation under constant-current operation, while this process intensifies during abrupt shutdown due to the presence of reverse current. Such accelerated cathodic degradation significantly undermines the long-term durability of the electrolyzer during practical operating. Here a fluorine-doped nickel-molybdenum oxide cathode is reported that maintains stability under both constant-current operation and startup-shutdown transitions. This full-cycle stability is achieved through a vacancy-mediated molybdate trap-and-buffer strategy. Vacancies generated by fluorine leaching under constant-current operation strongly trap molybdates, forming a negatively charged interfacial layer. This electron-enriched layer effectively buffers the active sites against overoxidation during abrupt shutdown. Meanwhile, its strong electrostatic-repulsion capability suppresses further dissolving of molybdenum and protects the electrode from chloride ion attack. As a result, an alkaline seawater electrolyzer assembled with the target catalyst operates stably for over 500 h at constant-current densities of 0.5 and 1.0 A cm¯². Notably, the electrolyzer maintains stable performance over 3900 startup-shutdown cycles with a minimal voltage degradation of only 0.02 mV per cycle.
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© 2025 Wiley-VCH GmbH