Interaction of O2 with Pd single crystals in the range 1-150 Torr: Surface morphology transformations |
| |
Authors: | Jinyi Han |
| |
Institution: | School of Chemical Engineering, Purdue University, Forney Hall of Chemical Engineering, Room 116, 480 Stadium Mall Drive, West Lafayette, IN 47907-2100, United States |
| |
Abstract: | The interaction of O2 with Pd single crystals including Pd(1 1 1), Pd(1 1 0) and Pd(1 0 0) in the pressure range 1-150 Torr was studied using scanning tunneling microscopy (STM). The Pd single crystal surface morphologies were determined by the oxidation conditions: O2 pressure, exposure time and treatment temperature. Oxygen dissolution into Pd metal followed by the formation of bulk oxide was observed. The dissolution of oxygen resulted in the increase of the inter-planar spacing between the first two layers, 9-14% increase after an exposure of Pd(1 1 1) to 10-25 Torr O2 at 600 K for 10 min, and 10-20% increase after exposing Pd(1 1 0) and Pd(1 0 0) to 1 Torr O2 at 600 K for 10 min. Elongated or semi-spherical oxide agglomerates along the steps nucleated and grew on both Pd(1 1 0) and Pd(1 0 0) surfaces after oxidation in 5-25 Torr O2 at 600 K. When bulk PdO was formed, the single crystal surface was covered with semi-spherical agglomerates 2-4 nm in size, which tended to aggregate to form a “cauliflower-like” structure. The single crystal surface area also increased during oxidation. |
| |
Keywords: | Palladium Palladium oxide Oxidation Oxygen Single crystal surfaces Scanning tunneling microscopy Surface morphology |
本文献已被 ScienceDirect 等数据库收录! |
|