C–doped TiO2(B): A density functional theory characterization

Abstract

Calculations based on the Density Functional Theory (DFT) were applied to study structural, electronic and optical properties of pure and C–doped TiO2(B) taking into account five different types of substitutional impurities. Our calculations indicate that the substitution of a C atom at an O site (C@O) is not only thermodynamically more favorable, but also independent of the growing conditions. The presence of impurity states in the band gap, along with a great reduction of the gap energy (Eg) were obtained after C@O doping, which leads to an enhancement of the absorbance in the visible and IR spectrum caused partially by trapped holes and electrons that the introduction of the impurity induces. Additionally, our results showed that the substitution of a C atom at a Ti site (C@Ti) originated a significant change not only in the structural arrangement of the neighborhood of the impurity, but also on its electronic and optical behavior compared to the pure TiO2(B) model.