A first-principles study of band structure modulation at TiO2 heterogeneous interfaces

To enhance the catalytic efficiency of titanium dioxide (TiO₂), functioning as a wide-band semiconductor, it is necessary to facilitate the separation of photogenerated charges by modulating its band structure. We constructed (TiO₂)_n/LaAlO₃ (n = 4–11) superlattice models and performed systematic first-principles calculations to investigate the modulation of the thickness of TiO₂ on its band structure at interfaces. The results demonstrate that the electrostatic potential differences in the superlattices are higher for the odd layers of TiO₂ than those for the even layers. On the other hand, the band gaps of TiO₂ at interfaces are all lower than that in the bulk TiO₂. As the thickness is increased from 4 to 11 layers, the band gap of TiO₂ at the Al-O terminated interface shows a gradual increase. In contrast, the band gap of TiO₂ at the La-O terminated interface exhibits fluctuations. These finds demonatrate the thickness and odd–even layers of TiO₂ in TiO₂/LaAlO₃ superlattices can effectively modulate the built-in electric field and the band gap of TiO₂ at interfaces.