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对金属氧化物光学气敏传感材料TiO2的探索与应用是当前研究的热点问题。采用基于密度泛函理论(DFT)中的平面波超软赝势方法,模拟计算CO2分子在锐钛矿型TiO2(101)表面的吸附行为,对吸附能,吸附距离,电子态密度以及光学性质进行分析。结果表明:CO2分子在含O空位表面的吸附效果优于无氧空位表面,且表面O空位的浓度越高,吸附效果越明显;分子平行于表面放置模型的吸附能为正值,吸附后的结构稳定,且以O端吸附为主,为此,分子平行于表面放置O端吸附于含两个O空位表面为最可能吸附模型;对电子态密度分析发现,当最佳模型吸附稳定后,含O空位表面为P型杂质,又有CO2分子中的2p电子掺入,在费米能级附近出现新峰值,改善了TiO2材料的光学性质,体现出较好的光学气敏传感特性。
The exploration and application of the metal oxide optical gas sensing material TiO2 is currently a hot issue. Adsorption behavior, adsorption distance, electron density and optical properties of CO2 molecules on the anatase TiO2 (101) surface were calculated using the plane wave super soft pseudopotential method based on density functional theory (DFT) analysis. The results show that the adsorption of CO2 molecules on the O-containing surface is better than that on the anoxic surface, and the higher the O-vacancy concentration, the more obvious the adsorption effect. The adsorption energy of the molecule parallel to the surface is positive, The structure is stable, and the main O-side adsorption, therefore, the molecule is placed parallel to the surface O-side adsorption containing two O vacancies surface is the most likely adsorption model; electronic state density analysis found that when the best model adsorption stability, The O vacancies contain P-type impurities and 2p electrons in the CO2 molecule. The new peak appears near the Fermi level, which improves the optical properties of the TiO2 material and shows good optical gas sensing properties.