Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Kohoku-Ku, Yokohama, 223-8522, Japan.
Phys Chem Chem Phys. 2018 Nov 21;20(45):28419-28424. doi: 10.1039/c8cp05998e.
The interactions between oxygen and Rh-Pd bimetallic alloy surfaces were investigated using surface sensitive experimental techniques and density functional theory calculations. The alloy surfaces were oxidized under 10-5 Torr and 100 mTorr oxygen upon heating above 250 °C. A thin Rh oxide layer was preferentially formed on a Rh1Pd9(100) surface, while a thin Pd oxide layer was formed on a Rh1Pd9(111) surface, though the Rh oxide is thermodynamically more stable irrespective of the surface orientation. Chemical analyses revealed that the initial Rh fraction for the (111) surface was significantly lower than that for the (100) surface, which suggests that the oxidized element on the surface is kinetically selected depending on the near surface initial composition.
采用表面敏感实验技术和密度泛函理论计算研究了氧与 Rh-Pd 双金属合金表面的相互作用。在加热至 250°C 以上时，将合金表面在 10-5 托和 100 毫托的氧气下氧化。在 Rh1Pd9(100)表面上优先形成薄的 Rh 氧化物层，而在 Rh1Pd9(111)表面上形成薄的 Pd 氧化物层，尽管 Rh 氧化物无论表面取向如何都是热力学上更稳定的。化学分析表明，（111）表面的初始 Rh 分数明显低于（100）表面的初始 Rh 分数，这表明表面上被氧化的元素是根据近表面初始组成在动力学上选择的。
