水煤气变换反应
从头算
氧气
氢
化学计量学
铂金
化学
空位缺陷
密度泛函理论
催化作用
从头算量子化学方法
氢化物
氧化物
化学物理
物理化学
分子
计算化学
结晶学
有机化学
生物化学
作者
Salai Cheettu Ammal,Andreas Heyden
摘要
The electronic structure of small Ptn (n = 1–8) clusters supported on the stoichiometric and partially reduced rutile TiO2(110) surface have been investigated using density functional theory. Pt atoms prefer to form a close-packed structure with (111) facet near an oxygen vacancy of the TiO2 support and a less dense structure with (100) facet away from oxygen vacant sites. The main focus of this study is on identifying a realistic catalyst model for the Pt/TiO2 interface under water-gas shift (WGS) reaction conditions. Constrained ab initio thermodynamic simulations on the stability of oxygen vacancies and formation of adsorbed gas phase molecules such as oxygen, CO, and hydrogen at the metal/oxide interface reveal that under WGS reaction conditions the formation of surface oxygen vacancies are thermodynamically favorable, platinum oxide species (PtOx) can easily be reduced and should not be present, CO adsorbs only weakly on interfacial Pt atoms, and CO poisoning of these sites should be less important. While hydrogen generally interacts weakly with interfacial Pt atoms, it forms very stable hydride species on Pt atoms neighboring an oxygen vacancy of the TiO2(110) support, possibly negatively affecting the WGS reaction rate.
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