Sha Qihao, Wang Shiyuan, Yan Li, Feng Yisui, Zhang Zhuang, Li Shihang, Guo Xinlong, Li Tianshui, Li Hui, Zhuang Zhongbin, Zhou Daojin, Liu Bin, Sun Xiaoming
State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing, People's Republic of China.
State Power Investment Corporation Hydrogen Energy Tech Co., Ltd., Beijing, People's Republic of China.
Nature. 2025 Mar;639(8054):360-367. doi: 10.1038/s41586-025-08610-1. Epub 2025 Mar 5.
Seawater electrolysis powered by renewable electricity provides an attractive strategy for producing green hydrogen. However, direct seawater electrolysis faces many challenges, primarily arising from corrosion and competing reactions at the anode caused by the abundance of halide ions (Cl, Br) in seawater. Previous studies on seawater electrolysis have mainly focused on the anode development, because the cathode operates at reducing potentials, which is not subject to electrode dissolution or chloride corrosion reactions during seawater electrolysis. However, renewable energy sources are intermittent, variable and random, which cause frequent start-shutdown operations if renewable electricity is used to drive seawater electrolysis. Here we first unveil dynamic evolution and degradation of seawater splitting cathode in intermittent electrolysis and, accordingly, propose construction of a catalyst's passivation layer to maintain the hydrogen evolution performance during operation. An in situ-formed phosphate passivation layer on the surface of NiCoP-CrO cathode can effectively protect metal active sites against oxidation during frequent discharge processes and repel halide ion adsorption on the cathode during shutdown conditions. We demonstrate that electrodes optimized using this design strategy can withstand fluctuating operation at 0.5 A cm for 10,000 h in alkaline seawater, with a voltage increase rate of only 0.5% khr. The newly discovered challenge and our proposed strategy herein offer new insights to facilitate the development of practical seawater splitting technologies powered by renewable electricity.
由可再生电力驱动的海水电解为生产绿色氢气提供了一种有吸引力的策略。然而，直接海水电解面临许多挑战，主要源于海水中大量卤离子（Cl、Br）在阳极引起的腐蚀和竞争反应。以往关于海水电解的研究主要集中在阳极开发上，因为阴极在还原电位下运行，在海水电解过程中不会发生电极溶解或氯化物腐蚀反应。然而，可再生能源具有间歇性、多变性和随机性，如果使用可再生电力驱动海水电解，会导致频繁的启停操作。在此，我们首次揭示了间歇电解过程中海水分解阴极的动态演变和降解情况，并据此提出构建催化剂钝化层以在运行过程中保持析氢性能。NiCoP-CrO阴极表面原位形成的磷酸盐钝化层可以在频繁放电过程中有效保护金属活性位点免受氧化，并在停机条件下排斥卤离子在阴极上的吸附。我们证明，采用这种设计策略优化的电极在碱性海水中以0.5 A cm的电流密度波动运行10000小时，电压增加速率仅为0.5%/千小时。本文新发现的挑战和我们提出的策略为推动实用的可再生电力驱动海水分解技术发展提供了新的见解。
