title: Controlled Synthesis of Carbon-Supported Gold Clusters for Rational Catalyst Design.
abstract: The development of novel catalysts based on metal clusters requires a rational design principle as well as atomically precise synthetic methods. Toward this goal, we have developed a method to precisely and independently control the size, composition, and surface modification of heterogeneous gold clusters by calcination of the ligand-protected Au clusters on carbon supports. We studied the effects of these structural parameters using benzyl alcohol oxidation as a test reaction. Unexpectedly, Au144and Au∼330on hierarchically porous carbon exhibited significantly higher turnover frequency than Au25and Au38. This size dependence is ascribed to the difference in the geometric structures of the Au clusters; Au144and Au∼330have an icosahedral-based structure whereas Au25and Au38have a face-centered cubic structure. Doping of a single Pd atom into Au25supported on carbon nanotubes remarkably enhanced the catalytic activity. The doping effect is explained in terms of the accelerated formation of the carbocation intermediate due to electron transfer from Pd to Au, since the doped Pd is buried within the Au clusters and is located at the interface between the supports. Residual thiolates on Au25affected both the activity and selectivity; selective oxidation to benzaldehyde was achieved at optimized coverage. Non-formation of benzoic acid is due to the suppression of oxidation activity by electron withdrawal by thiolates and non-formation of benzyl benzoate is due to the site-isolation effect by thiolates. These results will provide useful information for the rational design of gold-cluster-based catalysts with desired performance.
authors.affiliation: Department of Chemistry School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.|Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Yamazoe
authors.affiliation: Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.|Department of Materials Science and Engineering School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Rayong 21210, Thailand.
authors.forename: Tatchamapan
authors.initials: T
authors.lastname: Yoskamtorn
authors.affiliation: Department of Chemistry School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Takano
authors.affiliation: Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
authors.forename: Sudarat
authors.initials: S
authors.lastname: Yadnum
authors.affiliation: Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.|Department of Materials Science and Engineering School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Rayong 21210, Thailand.
authors.forename: Jumras
authors.initials: J
authors.lastname: Limtrakul
authors.affiliation: Department of Chemistry School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. tsukuda@chem.s.u-tokyo.ac.jp.|Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520, Japan. tsukuda@chem.s.u-tokyo.ac.jp.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Tsukuda
keywords: cluster compounds; doping; gold; oxidation; supported catalysts