The effect of the nature of substrate (Ge, Si and SnO2) on the band gap of TiO2 ultra-thin films: A promising new nanomaterial for solar energy technologies and the photocatalytic activity

Achieving an optimal band gap is a crucial step towards achieving efficiency and sustainability in many technological applications. In the present work, a computational investigation is carried out to explore the stability and the electronic properties of bulk and ultra-thin layers of TiO2 materials on a variety of substrates. The results show that the band structure of Titania-based materials can be tuned by designing ultra-thin layer devices that can affect the interatomic distances in a substrate engineering approach. Going from a band gap of about 3.0 eV for Bulk TiO2, a variety of layerings on different substrates is shown to yield a band gap in the 1.2-3.3 eV range. A titania multilayer device on tin oxide substrate is shown to lead to the important band gap of 1.2 eV, such a scheme can have tremendous applications for solar energy technologies and the photocatalytic activity of TiO2.