title: Active Surface Oxygen for Catalytic CO Oxidation on Pd(100) Proceeding under Near Ambient Pressure Conditions.
abstract: Catalytic CO oxidation reaction on a Pd(100) single-crystal surface under several hundred mTorr pressure conditions has been studied by ambient pressure X-ray photoelectron spectroscopy and mass spectroscopy. In-situ observation of the reaction reveals that two reaction pathways switch over alternatively depending on the surface temperature. At lower temperatures, the Pd(100) surface is covered by CO molecules and the CO2 formation rate is low, indicating CO poisoning. At higher temperatures above 190 °C, an O-Pd-O trilayer surface oxide phase is formed on the surface and the CO2 formation rate drastically increases. It is likely that the enhanced rate of CO2 formation is associated with an active oxygen species that is located at the surface of the trilayer oxide.
authors: †Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.
authors: Ryo
authors: R
authors: Toyoshima
authors: †Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.
authors: Masaaki
authors: M
authors: Yoshida
authors: †Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.
authors: Yuji
authors: Y
authors: Monya
authors: †Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.
authors: Kazuma
authors: K
authors: Suzuki
authors: §Department of Applied Physics, Hanyang University, ERICA 426-791, Republic of Korea.|∥Ertl Center for Electrochemistry and Catalysis, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
authors: Bongjin Simon
authors: BS
authors: Mun
authors: ‡Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
authors: Kenta
authors: K
authors: Amemiya
authors: ‡Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
authors: Kazuhiko
authors: K
authors: Mase
authors: †Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.
authors: Hiroshi
authors: H
authors: Kondoh
keywords: CO oxidation; Pd(100); ambient pressure XPS; mass spectroscopy; surface oxide; synchrotron radiation