Correlation between the surface electronic structure and CO-oxidation activity of Pt alloys

Hideki Abe; Hideki Yoshikawa; Naoto Umezawa; Ya Xu; Govindachetty Saravanan; Gubbala V. Ramesh; Toyokazu Tanabe; Rajesh Kodiyath; Shigenori Ueda; Nobuaki Sekido; Yoko Yamabe-Mitarai; Masahiko Shimoda; Takahisa Ohno; Futoshi Matsumoto; Takayuki Komatsu

doi:10.1039/C4CP03406F

Correlation between the surface electronic structure and CO-oxidation activity of Pt alloys†

Hideki Abe,*^ab Hideki Yoshikawa,^a Naoto Umezawa,^ab Ya Xu,^a Govindachetty Saravanan,^ac Gubbala V. Ramesh,*^a Toyokazu Tanabe,^a Rajesh Kodiyath,^a Shigenori Ueda,^d Nobuaki Sekido,^a Yoko Yamabe-Mitarai,^a Masahiko Shimoda,^a Takahisa Ohno,^a Futoshi Matsumoto^e and Takayuki Komatsu^f

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* Corresponding authors

^a National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
E-mail: ABE.Hideki@nims.go.jp, GUBBALA.Venkataramesh@nims.go.jp
Fax: +81-29-859-2301
Tel: +81-29-860-4806

^b Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama, Japan

^c CSIR-National Environmental Engineering Research Institute (CSIR-NEERI), Environmental Materials Division, Nehru Marg, Nagpur 440020, India

^d NIMS Beamline Station at SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan

^e Department of Material and Life Chemistry, Faculty of Engineering, Kanagawa University, 3-27-1, Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan

^f Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1-E1-10 Ookayama, Meguro-ku, Tokyo 185-8550, Japan

Abstract

The surface electronic structure and CO-oxidation activity of Pt and Pt alloys, Pt₃T (T = Ti, Hf, Ta, Pt), were investigated. At temperatures below 538 K, the CO-oxidation activities of Pt and Pt₃T increased in the order Pt < Pt₃Ti < Pt₃hHf < Pt₃Ta. The center-of-gravity of the Pt d-band (the d-band center) of Pt and Pt₃T was theoretically calculated to follow the trend Pt₃Ti < Pt₃Ta < Pt₃Hf < Pt. The CO-oxidation activity showed a volcano-type dependence on the d-band center, where Pt₃Ta exhibited a maximum in activity. Theoretical calculations demonstrated that the adsorption energy of CO on the catalyst surface monotonically decreases with the lowering of the d-band center because of diminished hybridization of the surface d-band and the lowest-unoccupied molecular orbital (LUMO) of CO. The observed volcano-type correlation between the d-band center and the CO oxidation activity is rationalized in terms of the CO adsorption energy, which counterbalances the surface coverage by CO and the rate of CO oxidation.

Physical Chemistry Chemical Physics

Correlation between the surface electronic structure and CO-oxidation activity of Pt alloys†

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Correlation between the surface electronic structure and CO-oxidation activity of Pt alloys

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