Komiya Hiroki, Laha Swastik, Obata Keisuke, Bhattacharyya Kalishankar, Takanabe Kazuhiro
Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
J Phys Chem Lett. 2025 Jun 19;16(24):6052-6058. doi: 10.1021/acs.jpclett.5c00704. Epub 2025 Jun 9.
The corrosion of anode materials caused by dissolved chloride ions (Cl) is considered one of the most significant issues in the long term durability of seawater electrolysis systems. This study examined the corrosion behaviors of Ni-based electrodes based on a dynamic potential-pH (Pourbaix) diagram with various buffered electrolytes (borate, carbonate, and phosphate). It was found that NiFeO/Ni plate electrodes degraded faster in media with mild pH than those with alkaline pH, and the corrosion rate depended on the dissolved ionic species in the presence of Cl, which could be explained in terms of the thermodynamic stability of the formed compounds on the surface. No significant corrosion was observed in phosphate-containing electrolytes, which could be explained by the high formation constant and the low solubility of the Ni-PO product with the formed complex. The density functional theory calculation was used to clarify the preferable phosphate adsorption on the Ni site over Cl, which stabilized Ni.
溶解的氯离子（Cl）引起的阳极材料腐蚀被认为是海水电解系统长期耐久性中最重要的问题之一。本研究基于动态电位-pH（Pourbaix）图，研究了镍基电极在各种缓冲电解质（硼酸盐、碳酸盐和磷酸盐）中的腐蚀行为。结果发现，NiFeO/Ni平板电极在pH值适中的介质中比在碱性pH值介质中降解更快，腐蚀速率取决于Cl存在时溶解的离子种类，这可以根据表面形成化合物的热力学稳定性来解释。在含磷酸盐的电解质中未观察到明显腐蚀，这可以用Ni-PO产物形成络合物的高形成常数和低溶解度来解释。采用密度泛函理论计算来阐明磷酸盐在Ni位点上比Cl更优先吸附，从而使Ni稳定。
