Impact of film thickness on the geometric and electronic characteristics of ultrathin rutile-TiO2(110) films supported by metal substrates

Abstract

Titanium dioxide (TiO₂) has received significant attention due to its importance in a wide range of applications, including photocatalysis, solar energy conversion, and chemical sensing. The physicochemical properties of TiO₂ can be finely tuned using a novel platform of ultrathin oxide films. In this study, a computational study based on density functional theory (DFT) calculations is performed to investigate the thickness-dependent geometric and electronic properties of ultrathin rutile-phase TiO₂(110) films supported by five body-centered cubic metal substrates: W, Mo, Ta, Nb, and V, oriented along the (100) plane. The DFT calculations suggest that W and Mo may serve as optimal metal substrates for the formation of ultrathin TiO₂ films, in which lattice mismatch along the long axis plays a significant role. Furthermore, the interfacial electronic structure of the TiO₂ film, primarily characterized by charge transfer from metal to the TiO₂ layer and the formation of metal-included gap states (MIGS), can be used to rationalize the thickness-dependent variation in the work function of ultrathin TiO₂ films on metal substrates. Our results provide valuable insights into the effect of the film thickness on the geometric and electronic properties of TiO₂ films grown on metal substrates.