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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Structural and Electrochemical Characterization of Metastable PtAu Bulk and Surface Alloys Prepared by Crossed-Beam Pulsed Laser Deposition
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Structural and Electrochemical Characterization of Metastable PtAu Bulk and Surface Alloys Prepared by Crossed-Beam Pulsed Laser Deposition

机译：交叉束脉冲激光沉积制备的亚稳态PtAu块状和表面合金的结构和电化学特性

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Crossed-beam pulsed laser deposition in a moderate He background gas pressure was used to prepare PtAu thin films. The Pt bulk content was determined by neutron activation analysis, whereas X-ray diffraction and X-ray photoelectron spectroscopy were used to assess the bulk and the surface structure of the films, respectively. It is shown that metastable PtAu alloys with a unique fcc structure are formed over the whole composition range. The surface composition of the films closely follows the bulk content, and X-ray photoelectron spectroscopy reveals that the surface of the films is also made of a PtAu alloy. These films are stable under ambient conditions. The electrochemical properties of these films were determined by cyclic voltammetry in H2SO4 electrolyte, and their reactivity toward the electrooxidation of CO and the electroreduction of O2 was assessed. The CO stripping peak potential value increases with the Au content, indicating an increased binding energy in comparison with polycrystalline Pt. Similarly, there is a cathodic shift of the Pt oxide reduction peak for the Au-rich alloy that indicates stronger Pt-O binding energies as compared with Pt-rich alloy electrodes. At the surface, the presence of Au in close proximity to Pt atoms induces a shift of the d-band center of the Pt atoms that translates into stronger bonds with CO- and O-containing species at the surface of the samples. As far as we can tell, the surface composition and structure of the deposits are not modified following the electrochemical measurements.
机译：在中等氦气背景气压下，用交叉光束脉冲激光沉积法制备PtAu薄膜。通过中子活化分析来确定Pt的体积含量，而使用X射线衍射和X射线光电子能谱分别评估膜的体积和表面结构。结果表明，在整个组成范围内形成了具有独特的fcc结构的亚稳态PtAu合金。膜的表面组成紧随体积含量，X射线光电子能谱显示膜的表面也由PtAu合金制成。这些薄膜在环境条件下是稳定的。通过循环伏安法在H2SO4电解质中测定这些膜的电化学性能，并评估其对CO电氧化和O2电还原的反应性。 CO汽提峰电位值随Au含量的增加而增加，表明与多晶Pt相比，结合能增加。类似地，富Au合金的Pt氧化物还原峰存在阴极位移，这表明与富Pt合金电极相比，Pt-O的结合能更强。在表面上，靠近Pt原子的Au的存在会引起Pt原子d谱带中心的移动，从而转变为与样品表面含CO和O的物种形成更牢固的键。据我们所知，在电化学测量后，沉积物的表面组成和结构没有改变。

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