晶格氧簇催化：从磁铁矿（001）载体到小Pt簇上的氧迁移示踪
Cluster Catalysis with Lattice Oxygen: Tracing Oxygen Transport from a Magnetite(001) Support onto Small Pt Clusters
摘要：
可还原氧化物负载的小金属簇上的氧化催化通常涉及晶格氧。在目前的工作中，我们跟踪的路径晶格氧从Fe_3O_4（001）到小Pt团簇在CO氧化过程中，旨在区分反应是否发生在团簇/支持界面或在团簇上。虽然氧空位在许多其他载体上形成，但由于高阳离子迁移率，磁铁矿在还原时保持其表面化学计量。为了研究大小依赖的氧亲和力是否起作用，我们研究了两个特定的簇大小，Pt 5和Pt 19。通过分离不同的反应步骤，晶格氧可以聚集在团簇上。程序升温脱附（TPD）和复杂的脉冲阀实验表明，CO的氧化发生在Pt团簇，而不是在界面上。扫描隧道显微镜（STM）表明，在减少的表观高度的集群，密度泛函理论（DFT）解释为重组后晶格氧反向溢出。
英文摘要：
Oxidation catalysis on reducible oxide-supported small metal clusters often involves lattice oxygen. In the present work, we trace the path of lattice oxygen from Fe3O4(001) onto small Pt clusters during the CO oxidation, aiming at differentiating whether the reaction takes place at the cluster/support interface or on the cluster. While oxygen vacancies form on many other supports, magnetite maintains its surface stoichiometry upon reduction thanks to a high cation mobility. In order to investigate whether size-dependent oxygen affinities play a role, we study two specific cluster sizes, Pt5 and Pt19. By separating different reaction steps in our experiment, lattice oxygen can be accumulated on the clusters. Temperature programmed desorption (TPD) and sophisticated pulsed valve experiments indicate that the CO oxidation takes place on the Pt clusters rather than at the interface. Scanning tunneling microscopy (STM) shows a decrease in apparent height of the clusters, which density functional theory (DFT) explains as a restructuring following lattice oxygen reverse spillover.
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