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基于密度泛函理论的第一性原理平面波超软赝势方法,计算了Zn吸附到TiO2(101)清洁表面、含有氧空位(VO)的缺陷表面以及既含有氧空位(VO)又含有羟基(-OH)表面的能量、Mulliken重叠布居数以及电子结构,并找到了Zn在每种表面的最稳定结构(分别为模型(c),模型(aI)以及模型(aII)).通过对三种表面稳定结构的分析、对比发现:首先,Zn原子吸附到清洁TiO2(101)表面上,主要与表面氧相互作用,形成Zn O共价键;其次,当Zn原子吸附到缺陷表面时,吸附能减小到1.75 eV,说明Zn更容易吸附到氧空位上(模型(aI));最后,纵观表面模型的能带结构以及态密度图发现,-OH的引入并没有引进新的杂质能级,Zn吸附此表面,即Zn-TiO2-VO-OH,使得禁带宽度缩短到最小(1.85 eV),从而有望提高TiO2的光催化活性.
Based on the first-principle plane-wave ultra-soft pseudopotential method based on density functional theory (DFT), the defect surface of Zn adsorbed on the clean surface of TiO2 (101), containing oxygen vacancies (VO) and the surface containing both oxygen vacancies (VO) -OH) surface energy, Mulliken overlap population number and electronic structure, and find the most stable structure of Zn on each surface (model (c), model (aI) and model (aII) First, the Zn atom adsorbed on the surface of the clean TiO2 (101) mainly interacted with the surface oxygen to form the Zn O covalent bond. Secondly, when the Zn atom adsorbed to the defect surface, the adsorption Can be reduced to 1.75 eV, indicating Zn is more easily adsorbed to the oxygen vacancies (model (aI)); Finally, looking at the band structure of the surface model and the density of states diagram found that the introduction of -OH did not introduce new impurities Zn adsorption on this surface, that is, Zn-TiO2-VO-OH, shortens the forbidden band width to the minimum (1.85 eV), which is expected to increase the photocatalytic activity of TiO2.