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    Trend of catalytic activity of CO oxidation on Rh and Ru nanoparticles: Role of surface oxide

    Year: 2012

    Journal: Catalysis Today, 2012, 185 (1), 131-137, 20131009

    Authors: Sunmi Kim, Kamran Qadir, Sookyoung Jin, A. Satyanarayana Reddy, Bora Seo, B.S. Munc, Sang Hoon Joo, Jeong Young Park

    Organizations: Graduate School of EEWS (WCU) and NanoCentury KI, KAIST (Korea Advanced Institute of Science and Technology), Daejeon 305-701, South Korea; School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 689-798, Republic of Korea; Department of Applied Physics, Hanyang University ERICA, Ansan 426-791, South Korea

    Recent studies suggest that surface oxides on transition metal nanoparticles play an important role in determining the catalytic activity of CO oxidation. In this work, we investigated the influence of surface modification of Rh and Ru nanoparticles on the catalytic activity of CO oxidation using UV-ozone surface treatment. Monodisperse Rh and Ru nanoparticles were synthesized by polyol reduction using poly(vinylpyrrolidone) (PVP) as a capping agent. The size of the nanoparticles was controlled by varying the concentration of the Rh and Ru precursors or using the seeded-growth method. The changes that occurred during UV-ozone surface treatment were characterized with X-ray photoelectron spectroscopy, which showed that the oxidation state increased after surface treatment. The catalytic activity and activation energy of Rh and Ru nanoparticle arrays were measured before and after the chemical modification. Our reaction studies indicate that the turnover rate of CO oxidation on Rh nanoparticles increases by a factor of three after UV-ozone treatment due to the formation of catalytically active Rh oxide. In contrast, the catalytic activity of Ru nanoparticles decreases after UV-ozone treatment, suggesting that the Ru bulk oxide formed during UV-ozone treatment is catalytically inactive. The results suggest an intriguing way to tune catalytic activity via engineering of the nanoscale surface oxide.