Analytical Sciences

Iron Oxyhydroxide Hierarchical Micro/Nanostructured Film as Catalyst for Electrochemical Oxygen Evolution Reaction

Ke-Hsuan WANG,*1 Genta WATANABE,*1 Hayato IKEUCHI,*1 Siyang CUI,*1 I-Ping LIU,*2 Kanta YAMADA,*3 Masaaki YOSHIDA,*3,*4 and Takeshi KAWAI*1

*1 Department of Industrial Chemistry, Tokyo University of Science, Shinjuku, Tokyo 162-8601, Japan
*2 Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan
*3 Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan
*4 Blue Energy Center for SGE Technology, Yamaguchi University, Ube, Yamaguchi 755-8611, Japan

A key requirement in developing oxygen evolution reaction (OER) electrocatalysts is increasing their surface area. Herein, we report the design of a hierarchical micro/nanostructured catalyst. Based on polystyrene colloidal template electrodeposition, an ordered microcup array surrounded by nanoflakes was fabricated. The effect of the deposition time on the formation of the catalyst and the corresponding OER performance of the catalyst were investigated using scanning electron microscopy, in situ X-ray absorption fine structure (XAFS) spectroscopy, and electrochemical analysis. The in situ XAFS measurements indicate that the structure of the hierarchical structured catalyst is similar to that of γ-FeOOH. The electrochemical analysis indicates that the hierarchical catalyst has a large surface area and a low charge transfer resistance, which lead to its excellent catalytic performance for the OER. Our study provides new insights in designing high-performance OER catalysts. Moreover, the synthesized hierarchical micro/nanostructured catalyst could be used as a platform for further studies on low-cost iron-based electrocatalysts.

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