Pt和Au修饰锐钛矿型TiO_2(101)面的第一性原理研究

First-principles Calculation on Pt- and Au-modified Anatase TiO_2(101) Surface

采用平面波超软赝势方法研究了Pt和Au修饰锐钛矿型TiO_2(101)面的结构稳定性及电子结构。结果显示贵金属原子在TiO_2(101)符合化学计量比的条件下,在其表面的吸附作用不强,对电子结构的影响也较小。但是发现在富O条件下,Pt和Au原子容易吸附在表面Ti空位的位置,与Au原子不同,Pt原子有从TiO_2表面扩散进入体相晶格中的趋势。而在富Ti条件下,Pt和Au原子容易吸附在O1空位的位置。对可能存在的几种空位缺陷吸附模型进行了电子结构的计算。结果表明:空位缺陷的产生不仅有利于Pt和Au原子"湿化"TiO_2(101)表面,也有利于带隙中产生贵金属原子的5d杂质能级。

Structure stability and electronic structures of anatase TiO2（101） surface modified by noble metal Pt and Au have been investigated using plane-wave ultrasoft pseudopotentials. The results show that the adsorption interaction is weak between noble atoms and anatase TiO2（101） surface, resulting in a slight effect on its electronic structure. However, under O-rich condition, it is found that Pt and Au atoms are favor of the Ti vacancies. Contrary to Au atom, Pt atom tends to diffuse from surface into bulk. Under Ti-rich condition, Pt and Au atoms are favor of the O vacancies. The calculated electronic structures of possible vacancy defects indicate that the appearance of surface vacancies not only avails to wet anatase TiO2（101） surfaces, but also enables their atoms to appear 5d impurity energy levels in band gap.