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Neutral Au₁-Doped Cluster Catalysts AuTi₂O₃–₆ for CO Oxidation by O₂

Chen, Jiao-Jiao, Li, Xiao-Na, Chen, Qiang, Liu, Qing-Yu, Jiang, Li-Xue, He, Sheng-Gui
Journal of the American Chemical Society 2018 v.141 no.5 pp. 2027-2034
carbon monoxide, catalysts, catalytic activity, gold, ionization, oxidation, oxygen, spectrometers, titanium dioxide
Oxide supported gold catalysts (e.g., Au/TiO₂) are of great significance in heterogeneous catalysis owing to their extraordinary catalytic activity. Study of heteronuclear metal oxide clusters (HMOCs, e.g., AuₓTiyOzq) is an important way to uncover the molecular-level mechanisms of gold catalysis in the related heterogeneous catalytic systems. However, the current studies of HMOCs are focused on charged clusters with little attention paid to neutral species. The reactivity study of neutral HMOCs is vital to have a comprehensive understanding of heterogeneous catalysis, but it is experimentally challenging because of the difficulty of cluster ionization and detection without fragmentation. Herein, benefiting from a homemade time-of-flight mass spectrometer coupled with a vacuum ultraviolet laser system, the reactivity of neutral Au₁-doped titanium oxide clusters AuTi₂O₃–₆ in catalytic CO oxidation by O₂ has been successfully identified. The mechanistic details of the catalysis have been elucidated by quantum chemistry calculations. The crucial roles of the mobile AuCO species that can facilitate not only the process of CO oxidation but also the process of O₂ activation have been discovered in the cluster catalysis. The fascinating results are of substantial importance to understand the mechanisms of CO oxidation over Au/TiO₂, one type of the best studied gold catalysts.