Chen Jiao-Jiao, Li Xiao-Na, Chen Qiang, Liu Qing-Yu, Jiang Li-Xue, He Sheng-Gui
State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.
University of Chinese Academy of Sciences , Beijing 100049 , China.
J Am Chem Soc. 2019 Feb 6;141(5):2027-2034. doi: 10.1021/jacs.8b11118. Epub 2019 Jan 14.
Oxide supported gold catalysts (e.g., Au/TiO) are of great significance in heterogeneous catalysis owing to their extraordinary catalytic activity. Study of heteronuclear metal oxide clusters (HMOCs, e.g., Au Ti O ) 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 Au-doped titanium oxide clusters AuTiO in catalytic CO oxidation by O 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 O activation have been discovered in the cluster catalysis. The fascinating results are of substantial importance to understand the mechanisms of CO oxidation over Au/TiO, one type of the best studied gold catalysts.
氧化物负载的金催化剂（如Au/TiO）由于其非凡的催化活性，在多相催化中具有重要意义。研究异核金属氧化物簇（HMOCs，如AuTi₂O₄）是揭示相关多相催化体系中金催化分子水平机制的重要途径。然而，目前对HMOCs的研究主要集中在带电簇上，对中性物种关注较少。中性HMOCs的反应性研究对于全面理解多相催化至关重要，但由于在不发生碎片化的情况下进行簇离子化和检测困难，其实验具有挑战性。在此，受益于自制的飞行时间质谱仪与真空紫外激光系统的结合，成功确定了中性掺金二氧化钛簇AuTiO在O₂催化CO氧化中的反应性。通过量子化学计算阐明了催化的机理细节。在簇催化中发现了可移动的AuCO物种不仅促进CO氧化过程，还促进O₂活化过程的关键作用。这些引人入胜的结果对于理解Au/TiO（一种研究最多的金催化剂类型）上CO氧化的机理具有重要意义。
