Ultrathin oxide shell coating of metal nanoparticles using ionic liquid/metal sputteringElectronic supplementary information (ESI) available: TEM images, XPS spectra, and cyclic voltammograms of metal@In2O3 particles. See DOI: 10.1039/c4ta06643j

• Main Authors: Torimoto, Tsukasa, Ohta, Yasuhiro, Enokida, Kazuki, Sugioka, Daisuke, Kameyama, Tatsuya, Yamamoto, Takahisa, Shibayama, Tamaki, Yoshii, Kazuki, Tsuda, Tetsuya, Kuwabata, Susumu
• Format: Journal Article
• Language: English
• Published: 03.03.2015
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c4ta06643j

The surface coating of metal nanoparticles resulting into core-shell structures is expected to improve the physicochemical properties of the nanoparticle cores without changing their size and shape. Here, we developed a novel strategy to coat Au, AuPd or Pt catalyst cores having average sizes smaller than 2.5 nm, which were pre-synthesized in ionic liquids by corresponding metal sputtering, with an extremely thin In 2 O 3 layer ( ca. <1.5 nm) by sputter deposition of indium in a room-temperature ionic liquid. The metal cores of Au or AuPd in core-shell particles exhibited superior stability against heat treatments or during electrocatalytic reactions compared to the corresponding bare metal particles. The In 2 O 3 shell coating considerably enhanced the durability of electrocatalytically active Pt particles (1.2 nm). This sequential metal sputter deposition of different metals in ionic liquids will considerably contribute to the exploitation of key nanostructured components for next-generation energy-conversion systems. The indium sputter deposition into ionic liquids containing noble metal nanoparticles produces core-shell-structured metal@In 2 O 3 with high thermal and electrochemical stability.