Harada Kazuki, Sakai Arisu, Tsunekawa Shun, Takaki Yuji, Nagasaka Masanari, Yuzawa Hayato, Wang Ke-Hsuan, Ina Toshiaki, Kondoh Hiroshi, Yoshida Masaaki
Department of Applied Chemistry, Yamaguchi University, Tokiwadai, Ube, 755-8611, Yamaguchi, Japan.
Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki, 444-8585, Aichi, Japan.
ChemSusChem. 2025 Aug 6;18(16):e202500559. doi: 10.1002/cssc.202500559. Epub 2025 Jul 8.
Cobalt oxide electrocatalysts electrodeposited from carbonate-based electrolyte solutions (Co-C) and exhibiting high oxygen evolution reaction (OER) activity at neutral pH are investigated using operando hard/soft X-ray absorption fine structure (XAFS) analyses. Operando Co K-edge XAFS data indicate that the Co-C comprises a collection of CoOOH nanoclusters and that the Co in this material is oxidized to higher valence states upon applying an electrode potential. Operando C K-edge XAFS results show that carbonate anions are adsorbed on the CoOOH nanoclusters and that this phenomenon is promoted at the active potential for the OER. The carbonate anions are found to remain adsorbed on the CoOOH and to be catalytically active even in unbuffered solutions without carbonate anions. The carbonate anions evidently stabilize the active sites associated with Co to enhance the electrocatalytic activity. This study provides new insights into the function of anions adsorbed on CoOOH nanoclusters, and the results of this work should be applicable to a wide range of metal oxide catalysts in neutral solutions.
采用原位硬/软X射线吸收精细结构（XAFS）分析方法，对从碳酸盐基电解质溶液中电沉积得到的氧化钴电催化剂（Co-C）进行了研究，该催化剂在中性pH值下表现出高析氧反应（OER）活性。原位Co K边XAFS数据表明，Co-C由CoOOH纳米团簇组成，并且在施加电极电位时，该材料中的Co被氧化为更高的价态。原位C K边XAFS结果表明，碳酸根阴离子吸附在CoOOH纳米团簇上，并且在OER的活性电位下这种现象会增强。发现碳酸根阴离子即使在没有碳酸根阴离子的无缓冲溶液中也会吸附在CoOOH上并具有催化活性。碳酸根阴离子显然稳定了与Co相关的活性位点，从而增强了电催化活性。这项研究为吸附在CoOOH纳米团簇上的阴离子的功能提供了新的见解，并且这项工作的结果应该适用于中性溶液中的广泛金属氧化物催化剂。
