Di Liberto Giovanni, Tosoni Sergio, Pacchioni Gianfranco
Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via R Cozzi 55, 20125 Milano, Italy.
J Phys Condens Matter. 2021 Feb 17;33(7):075001. doi: 10.1088/1361-648X/abc357.
In this work we investigate TiO and BiVO nanostructures by means of density functional theory (DFT) calculations, to provide an estimate of the band alignment in TiO/BiVO interfaces, highly active in photo-electrochemistry and photocatalytic water splitting. Calculations were carried out with both DFT range separated and self-consistent dielectric dependent hybrid functionals (HSE06 and PBE0). The impact of systems' size has been investigated. The converged electronic levels of TiO and BiVO surfaces have been used to predict the band alignment in TiO/BiVO heterostructures. Results indicated that when TiO (101) surface is matched with BiVO (110), a type-II alignment is obtained, where the band edges of BiVO are higher in energy that those of TiO. This picture is favorable for charge-carriers separation upon photoexcitation, where electrons move toward TiO and holes toward BiVO. On the contrary, if TiO (101) is interfaced to BiVO (010) the offset between the band edges is negligible, thus reducing the driving force toward separation of charge carriers. These results rationalize the dependence on the facet's exposure of the observed photocatalytic performances of TiO/BiVO composites, where the TiO (101)/BiVO (110) interface outperforms the TiO (101)/BiVO (010) one.
在这项工作中，我们通过密度泛函理论（DFT）计算研究了TiO和BiVO纳米结构，以估计在光电化学和光催化水分解中具有高活性的TiO/BiVO界面中的能带排列。使用DFT范围分离和自洽介电相关杂化泛函（HSE06和PBE0）进行了计算。研究了体系尺寸的影响。TiO和BiVO表面的收敛电子能级已用于预测TiO/BiVO异质结构中的能带排列。结果表明，当TiO（101）表面与BiVO（110）匹配时，会获得II型排列，其中BiVO的能带边缘能量高于TiO的能带边缘能量。这种情况有利于光激发时电荷载流子的分离，此时电子向TiO移动，空穴向BiVO移动。相反，如果TiO（101）与BiVO（010）形成界面，则能带边缘之间的偏移可以忽略不计，从而降低了电荷载流子分离的驱动力。这些结果解释了TiO/BiVO复合材料观察到的光催化性能对晶面暴露的依赖性，其中TiO（101）/BiVO（110）界面优于TiO（101）/BiVO（010）界面。
