Analytical Sciences

Abstract − Analytical Sciences, 36(1), 35 (2020).

Improvement in Cobalt Phosphate Electrocatalyst Activity toward Oxygen Evolution from Water by Glycine Molecule Addition and Functional Details
Kanta YAMADA,*1 Tomoki HIUE,*2 Toshiaki INA,*3 Kehsuan WANG,*4 Hiroshi KONDOH,*2 Yoshihisa SAKATA,*1 Yuh-Lang LEE,*5 Takeshi KAWAI,*4 and Masaaki YOSHIDA*1,*6
*1 Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Tokiwadai, Ube, Yamaguchi 755-8611, Japan
*2 Department of Chemistry, Keio University, Hiyoshi, Yokohama, Kanagawa 223-8522, Japan
*3 Japan Synchrotron Radiation Research Institute (JASRI, SPring-8), Sayo, Hyogo 679-5198, Japan
*4 Department of Industrial Chemistry, Tokyo University of Science, Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
*5 Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
*6 Blue Energy Center for SGE Technology (BEST), Yamaguchi University, Tokiwadai, Ube, Yamaguchi 755-8611, Japan
Electrochemical water splitting using renewable energy shows promise for the development of sustainable hydrogen production methods. The process requires a highly active electrocatalyst for oxygen evolution to improve the overall water splitting efficiency. The present study showed that oxygen evolution improved dramatically upon the addition of glycine to cobalt phosphate, when the glycine was added to the electrolyte solution during electrodeposition. The functionality of the organic molecules was investigated using in situ UV-vis absorption, in situ X-ray absorption fine structure, and in situ infrared (IR) absorption spectroscopy in the attenuated total reflection mode. The results demonstrated that the glycine molecules assembled cobalt oxide clusters composed of CoO6 (CoOOH) octahedrons a few nanometers in diameter upon the electrodeposition of cobalt catalysts. This suggests that the cobalt-glycine catalyst can decompose water to oxygen gas efficiently, because the number of cobalt oxide clusters increased as active reaction sites upon the addition of glycine molecules.