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首页> 外文期刊>ACS catalysis >CO Oxidation at the Au/TiO2 Boundary: The Role of the Au/Ti-5c Site
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CO Oxidation at the Au/TiO2 Boundary: The Role of the Au/Ti-5c Site

机译：Au / TiO2边界处的CO氧化：Au / Ti-5c位点的作用

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摘要

Density functional theory is used to determine the reaction mechanisms of CO oxidation and the active oxygen species on a Au/TiO2 model catalyst. The model consists of a Au rod supported along the TiO2 [1 (1) over bar0] direction of the TiO2(110) surface. An interfacial Au/Ti5c site at the interface boundary is identified to be particularly active toward O-2 adsorption and dissociation. At this site, O-2 dissociation has an energy barrier of 0.5 eV, which is facile at room temperature. The resulting adsorbed Au/O/Ti-5c oxygen species are shown to be stable and active for CO oxidation under relevant reaction conditions with an activation energy of 0.24 eV. Furthermore, the adsorbed Au/O/Ti5c oxygen species functions as an electron reservoir, and it lowers the oxygen vacancy formation energy of a surface lattice oxygen (Obri), as well as the Ti interstitial formation energy, due to electron transfer from high-energy defect states to low-energy p-states of the adsorbed Au/O/Ti5c oxygen species. Hence, the Obri species is activated at the oxidized Au/TiO2 interface boundary and the energy barrier of CO oxidation with Obri is calculated to be 0.55 eV. Thus, the CO oxidation reaction can proceed at room temperature either via a Langmuir-Hinshelwood mechanism with an adsorbed Au/O/Ti-5c oxygen species or via a Au-assisted Mars-van Krevelen mechanism with Obri.
机译：密度泛函理论用于确定Au / TiO2模型催化剂上CO氧化与活性氧种类的反应机理。该模型由沿TiO2 [110（1）的bar0]方向沿TiO2（110）表面支撑的Au棒组成。界面边界处的Au / Ti5c界面位点对O-2的吸附和解离特别有效。在这个位置，O-2离解的能垒为0.5 eV，在室温下很容易。所产生的吸附的Au / O / Ti-5c氧物种在相关的反应条件下具有0.24 eV的活化能，对于CO氧化是稳定和有活性的。此外，吸附的Au / O / Ti5c氧物种起着电子储库的作用，并且由于来自高能态的电子转移，降低了表面晶格氧（Obri）的氧空位形成能以及Ti间隙形成能。能量缺陷状态变为吸附的Au / O / Ti5c氧物种的低能p状态。因此，Obri物种在氧化的Au / TiO2界面边界处被激活，并且用Obri进行的CO氧化的能垒经计算为0.55 eV。因此，CO氧化反应可以在室温下通过具有吸附的Au / O / Ti-5c氧物种的Langmuir-Hinshelwood机理或通过具有Obri的Au辅助的Mars-van Krevelen机理进行。

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