Surface Chemistry of Model Oxide-Supported Metal Catalysts: An Overview of Gold on Titania

摘要: Insight into atomic-level surface chemistry of metals on oxide surfaces is vital to understanding heterogeneous catalysis. In this work, scanning tunneling microscopy (STM) in conjunction with traditional science techniques used study gold metal clusters a planar titania support. When Au vapor-deposited onto TiO2(110) under ultra-high vacuum (UHV) conditions, it grows as three-dimensional (3D) hemispherical TiO2(110), indicative Volmer-Weber (VW) growth mode. However, at very low coverages (0.01–0.05 ML), quasi-two-dimensional (quasi-2D) are observed. Annealing studies reveal that form large microcrystals well-defined hexagonal shapes above 1000 K. Furthermore, an oxygen-induced cluster ripening observed after Au/TiO2(110) exposed 10.00 Torr O2 elevated pressure reactor. The morphological change induced by exposure suggests chemisorption both the and TiO2 substrate room temperature. exhibit clear bimodal size distribution due Ostwald ripening: some increase while others shrink.