Investigation of Size Effect of Ag Nanoparticles on Oxygen Reduction Reaction Using Ag/Co/C Catalysts Prepared by Galvanic Deposition Method
Ag nanoparticles (AgNPs) were prepared by a galvanic reaction between Ag+ ions and Co metal particles supported on carbon. Variation of the preparation conditions provided a series of AgNPs with various sizes (ca. 2–12 nm). By using the various AgNPs, the size effect on the oxygen reduction reaction activity was investigated. The mass activity of AgNPs increased with a decrease of the size. On the other hand, the Ag-surface-area-specific activity decreased with a decrease of the size.
KeywordsElectrocatalysis Fuel cells
This work was supported by Grant-in-Aids from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan “Elements Strategy Initiative to Form Core Research Center” Program (since 2012) and for challenging Exploratory Research (No. 26630408). The XAFS measurements were carried out at Photon Factory at High Energy Accelerator Research Organization (KEK-PF), Tsukuba, Japan (Approval No. 2012G763) and at SPring-8 of the Japan Synchrotron Radiation Research Institute (JASRI), Hyogo, Japan (Approval No. 2013B1421). The authors thank Prof. Tatsuya Takeguchi (Iwate Univ.), Prof. Wataru Sugimoto (Sinshu Univ.), and Prof. Tsukasa Torimoto (Nagoya Univ.) for the electrochemical measurement, Dr. Seiji Yamazoe (The University of Tokyo) for the XAFS measurement at SPring-8, and Mr. Shin Watanabe (Tokuyama Corp.) for the supply of AS-4 ionomer solution.
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