Gold Cluster-CeO₂ Nanostructured Hybrid Architectures as Catalysts for Selective Oxidation of Inert Hydrocarbons

Gold clusters with ultrasmall size and special structure are highly attractive for heterogeneous catalysis. However, stabilizing gold clusters under thermal treatment remains a major hurdle on the way toward real-world application. Herein, we report an effective approach that stabilizing gold clusters (Au₂₅ and Au₁₄₄) within mesoporous ceria nanospheres via a two phase overcoating process. High-resolution aberration-corrected STEM studies indicated that gold clusters were encapsulated and confined in the intersectional channels of ceria, and the encapsulated clusters were demonstrated to be resistant to sintering under high-temperature thermal treatment. The solvent-free aerobic oxidation of toluene and ethylbenzene was carried out to illustrate the performance of gold clusters in catalysis, and these materials showed excellent catalytic activities and afforded much higher turnover frequencies (up to 5634 and 55027 turnovers for toluene and ethylbenzene oxidation), which are, as far as we know, much higher than the values of state-of-art catalysts. Density functional theory calculations revealed that the encapsulated gold clusters effectively reduced the energy required for the dissociation of O₂ molecules, leading to the excellent catalytic activity.