Zhang Sixie, Wang Yunan, Li Shuyu, Wang Zhongfeng, Chen Haocheng, Yi Li, Chen Xu, Yang Qihao, Xu Wenwen, Wang Aiying, Lu Zhiyi
Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, Zhejiang, P. R. China.
Qianwan institute of CNITECH, Ningbo, 315201, Zhejiang, P. R. China.
Nat Commun. 2023 Aug 10;14(1):4822. doi: 10.1038/s41467-023-40563-9.
The corrosive anions (e.g., Cl) have been recognized as the origins to cause severe corrosion of anode during seawater electrolysis, while in experiments it is found that natural seawater (0.41 M Cl) is usually more corrosive than simulated seawater (0.5 M Cl). Here we elucidate that besides Cl, Br in seawater is even more harmful to Ni-based anodes because of the inferior corrosion resistance and faster corrosion kinetics in bromide than in chloride. Experimental and simulated results reveal that Cl corrodes locally to form narrow-deep pits while Br etches extensively to generate shallow-wide pits, which can be attributed to the fast diffusion kinetics of Cl and the lower reaction energy of Br in the passivation layer. Additionally, for the Ni-based electrodes with catalysts (e.g., NiFe-LDH) loading on the surface, Br causes extensive spalling of the catalyst layer, resulting in rapid performance degradation. This work clearly points out that, in addition to anti-Cl corrosion, designing anti-Br corrosion anodes is even more crucial for future application of seawater electrolysis.
腐蚀性阴离子（如Cl）已被认为是海水电解过程中导致阳极严重腐蚀的根源，而实验发现天然海水（约0.41M Cl）通常比模拟海水（约0.5M Cl）腐蚀性更强。在此我们阐明，除了Cl之外，海水中的Br对镍基阳极的危害更大，因为在溴化物中其耐腐蚀性较差且腐蚀动力学比氯化物中更快。实验和模拟结果表明，Cl局部腐蚀形成窄而深的坑，而Br广泛蚀刻形成浅而宽的坑，这可归因于Cl的快速扩散动力学以及Br在钝化层中的较低反应能。此外，对于表面负载有催化剂（如NiFe-LDH）的镍基电极，Br会导致催化剂层大量剥落，从而导致性能迅速下降。这项工作明确指出，除了抗Cl腐蚀外，设计抗Br腐蚀的阳极对于海水电解的未来应用更为关键。
