Oxidation of monometallic Pd and bimetallic Pd₃Au alloy surfaces are observed by in situ ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) at an elevated pressure (100 mTorr O₂ ambient). It is directly evidenced that the alloying with Au hinders the surface oxidation of Pd₃Au surfaces compared with monometallic Pd surfaces. Remarkably, the oxidation behavior is clearly different between Pd₃Au(111) and (100) surfaces. The (100) surface has a relatively Pd-rich surface composition, and the surface oxide layer is formed, whereas the (111) surface has a Au-rich composition, and the surface oxidation is quite limited. A combined approach of experimental and theoretical techniques reveals that Pd/Au surface composition and atomic arrangement are key factors determining the oxidation behavior.

中文翻译：

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Pd-Au合金表面氧化的取向依赖性阻碍

通过在升高的压力（100 mTorr O ₂环境）下的原位环境压力X射线光电子能谱（AP-XPS）观察到单金属Pd和双金属Pd ₃ Au合金表面的氧化。直接证明与单金属Pd表面相比，与Au的合金化阻碍了Pd ₃ Au表面的表面氧化。值得注意的是，Pd ₃之间的氧化行为明显不同Au（111）和（100）表面。（100）表面具有相对富Pd的表面组成，并且形成了表面氧化物层，而（111）表面具有富Au的组成，并且表面氧化受到很大限制。实验和理论技术的组合方法表明，Pd / Au表面组成和原子排列是决定氧化行为的关键因素。