CO oxidation over ceria supported Au22 nanoclusters: Shape effect of the support

• Published in: Chinese chemical letters 2018-06, Vol.29 (6), p.795-799
• Main Authors: Wu, Zili, Mullins, David R., Allard, Lawrence F., Zhang, Qianfan, Wang, Laisheng
• Format: Article
• Language: English
• Subjects: Ceria; CO oxidation; Gold nanoclusters; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ligands; MATERIALS SCIENCE; Support shape
• ISSN: 1001-8417; 1878-5964
• DOI: 10.1016/j.cclet.2018.01.038

[Display omitted] CO oxidation over ceria-supported Au22 nanoclusters shows strong dependence on the support shape: the lattice oxygen in CeO2 rods is more reactive than in the cubes and thus make rods a superior support for Au nanoclusters in catalyzing low temperature CO oxidation. Gold (Au) nanoclusters have recently emerged as ideal models for understanding Au catalysis, because the nanosized Au particles have precise atomic numbers and uniform size. In this work, we studied for the first time the support shape effect on the catalysis of Au nanoclusters by using CO oxidation as a model reaction. Au22(L8)6 (L=1,8-bis(diphenylphosphino) octane) nanoclusters were supported on CeO2 rods or cubes, then pretreated at different temperatures (up to 673K), allowing the gradual removal of the organic phosphine ligands. CO oxidation test over these differently pretreated samples shows that CeO2 rods are much better supports than cubes for Au22 nanoclusters in enhancing the reaction rate. In situ IR spectroscopy coupled with CO adsorption indicates that the shape of CeO2 support can impact the nature and quantity of exposed Au sites, as well as the efficiency of organic ligand removal. Although CeO2 rods are helpful in exposing a greater percentage of total Au sites upon ligands removal, the percentage of active Au sites (denoted by Auδ+, 0