Composition control of alloy nanoparticles consisting of bulk-immiscible Au and Rh metals via an ionic liquid/metal sputtering technique for improving their electrocatalytic activity

Kazutaka Akiyoshi; Yumezo Watanabe; Tatsuya Kameyama; Tokuhisa Kawawaki; Yuichi Negishi; Susumu Kuwabata; Tsukasa Torimoto

doi:10.1039/d2cp01461k

Composition control of alloy nanoparticles consisting of bulk-immiscible Au and Rh metals via an ionic liquid/metal sputtering technique for improving their electrocatalytic activity

Phys Chem Chem Phys. 2022 Oct 12;24(39):24335-24344. doi: 10.1039/d2cp01461k.

Authors

Kazutaka Akiyoshi¹, Yumezo Watanabe¹, Tatsuya Kameyama¹, Tokuhisa Kawawaki^{2

3}, Yuichi Negishi^{2

3}, Susumu Kuwabata⁴, Tsukasa Torimoto¹

Affiliations

¹ Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan. torimoto@chembio.nagoya-u.ac.jp.
² Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.
³ Research Institute for Science and Technology, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.
⁴ Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.

PMID: 36177988
DOI: 10.1039/d2cp01461k

Abstract

AuRh bimetallic alloy nanoparticles (NPs) were successfully prepared by simultaneous sputtering of Au and Rh in a room-temperature ionic liquid (RTIL) of N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF₄). Bimetallic AuRh alloy NPs of 1-2 nm in size were formed in the RTIL. The alloy composition was controllable by changing the surface areas of Au and Rh plates used as sputtering targets. Loading thus-obtained AuRh NPs on carbon black (CB) powders increased the size of AuRh NPs to ca. 2-8 nm, depending on the Au/Rh ratio. The electrocatalytic activity for oxygen reduction reaction (ORR) of AuRh NP-loaded CB catalysts showed a volcano-type dependence on their composition, in which AuRh NPs with Au surface coverage of 62% exhibited the optimal ORR activity, the specific activity being ca. 5 times higher than that of pure Rh NPs.