Controlling the oxidation state of molybdenum oxide nanoparticles prepared by ionic liquid/metal sputtering to enhance plasmon-induced charge separation

Kazutaka Akiyoshi; Tatsuya Kameyama; Takahisa Yamamoto; Susumu Kuwabata; Tetsu Tatsuma; Tsukasa Torimoto

doi:10.1039/d0ra05165a

Controlling the oxidation state of molybdenum oxide nanoparticles prepared by ionic liquid/metal sputtering to enhance plasmon-induced charge separation

RSC Adv. 2020 Aug 3;10(48):28516-28522. doi: 10.1039/d0ra05165a.

Authors

Kazutaka Akiyoshi¹, Tatsuya Kameyama¹, Takahisa Yamamoto¹, Susumu Kuwabata², Tetsu Tatsuma³, Tsukasa Torimoto¹

Affiliations

¹ Graduate School of Engineering, Nagoya University Furo-cho, Chikusa-ku Nagoya 464-8603 Japan torimoto@apchem.nagoya-u.ac.jp.
² Graduate School of Engineering, Osaka University 2-1 Yamada-oka Suita Osaka 565-0871 Japan.
³ Institute of Industrial Science, The University of Tokyo 4-6-1 Komaba, Meguro-ku Tokyo 153-8505 Japan.

Abstract

Nanoparticles composed of molybdenum oxide, MoO _x , were successfully prepared by room-temperature ionic liquid (RTIL)/metal sputtering followed by heat treatment. Hydroxyl groups in RTIL molecules retarded the coalescence between MoO _x NPs during heat treatment at 473 K in air, while the oxidation state of Mo species in MoO _x nanoparticles (NPs) could be modified by changing the heat treatment time. An LSPR peak was observed at 840 nm in the near-IR region for MoO _x NPs of 55 nm or larger in size that were annealed in a hydroxyl-functionalized RTIL. Photoexcitation of the LSPR peak of MoO _x NPs induced electron transfer from NPs to ITO electrodes.