The Quest for Stability: Structural Dependence of Rh(111) on Oxygen Coverage at Elevated Temperature
The Quest for Stability: Structural Dependence of Rh(111) on Oxygen Coverage at Elevated Temperature
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DOI：
10.1021/acs.jpcc.7b02738
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发表时间：
2017-05-18
影响因子：
3.7
通讯作者：
Killelea, Daniel R.
中科院分区：
文献类型：
--
作者：
Farber, Rachael G.;Turano, Marie E.;Killelea, Daniel R.
最近的研究表明，氧化物表面在多相催化反应中的重要性。由于重复制备氧化金属表面的困难，人们往往不清楚哪些物种在热力学上是稳定的，哪些因素影响氧化物的形成过程。在这项工作中，我们证明了在Rh(111)表面暴露于原子氧后的热力学稳定相是(2x1)O附着层和三层表面氧化物RhO2。表面缺陷和次表面区溶解O原子浓度的增加促进了RhO2的形成。随着亚表面O原子浓度的降低，RhO2的覆盖度减小，表面只有(2×1)O附着层。地下氧物种在RhO2形成和稳定性中的重要性表明表面结构和地下氧浓度之间存在复杂的关系。
Recent studies have shown the importance of oxide surfaces in heterogeneously catalyzed reactions. Because of the difficulties in reproducibly preparing oxidized metal surfaces, it is often unclear what species are thermodynamically stable and what factors effect the oxide formation process. In this work, we show that the thermodynamically stable phases on Rh(111) after exposure to atomic oxygen are the (2X1) O adlayer and the trilayer surface oxide, RhO2. Formation of RhO2, was facilitated by surface defects and elevated concentrations of dissolved O atoms in the subsurface region. As the concentration of subsurface O atoms decreased, the coverage of RhO2, decreased so that only the (2X1) O adlayer was present on the surface. The importance of subsurface oxygen species in RhO2 formation and stability indicates a complex relationship between surface structure and subsurface oxygen concentration.