锐钛矿TiO2（101）表面电子能带结构的理论研究

二氧化钛作为一种理想的光催化和光电转换半导体材料，受到了广泛的关注和研究，其表面的电子能带结构作为其本征的化学性质之一，决定着表面上氧化还原反应发生的可能性. 对二氧化钛表面电子能带结构进行深入研究对于我们从微观上认识并改良二氧化钛这一光电催化材料，以及进一步开发利用更好的光催化材料都具有非常好的指导意义. 本论文采用密度泛函理论，计算研究了锐钛矿TiO₂（101）表面的电子能带结构，并通过与金红石TiO₂（110）晶面的对比，系统分析了两个表面电子能带结构的不同以及水分子的溶剂化作用对电子能带结构的影响.

Aligning Electronic Energy Levels on the Anatase TiO2(101) Surface

As one of the most commonly-used materials for photocatalysis and solar energy conversion, titanium dioxide (TiO₂) has been extensively studied for more than 40 years. Its photoelectrochemical activity crucially depends on the band positions at the interface. In this work, the valence band maximum (VBM) and conduction band minimum (CBM) of a model TiO₂ surface are computed using the standard work function method at the level of Perdew-Burke-Ernzerhof (PBE) density functional, which are then converted to the scale of the standard hydrogen electrode (SHE) by subtracting the absolute SHE potential. Comparing with the rutile TiO₂(110) surface, we find a similar upshift in the VBM and CBM upon the adsorption of water molecules on the anatase TiO₂(101) surface, and the band gap error intrinsic to the PBE functional can be mainly attributable to mis-positioning of the VBM. In addition, in contrast to the finding on the rutile TiO₂(110) surface that the adsorption of 1 monolayer water largely recovers the band alignment of the aqueous interface, our preliminary calculations indicate that on the anatase TiO₂(101) surface there is a considerable difference between the simplified model with the adsorption of 1 monolayer water and the fully solvated interface, suggesting the necessity to include the water molecules beyond the first adsorption layer in order to realistically represent the anatase TiO₂ water interface.