Incorporating Nitrogen Atoms at TiO2 Lattice Sites for Improved Transparency and Visible-Light Photocatalytic Activity

Doping nitrogen into titanium dioxide (N-TiO2) is vital to extend itsphotocatalytic activity to the visible-light range. However, thisoften leads to a significant decrease in film transparency, whichhinders its usage in environmental applications. In this study, wereport the deposition of N-TiO2 films with a visible-lightactivity and improved transparency. Using pulsed magnetron sputtering,we achieve a high concentration (& SIM;7.5%) of nitrogen incorporationinto anatase TiO2 films. This results in a much-reducedband gap (& SIM;1.92 eV) and remarkable photocatalytic performancein the visible-light range. More importantly, the transparency ofthe films does not decrease significantly even at this high dopingconcentration, in contrast to the samples prepared using the conventionaldirect current (DC) sputtering process. First-principles calculationsindicate that the improved incorporation of nitrogen at the substitutionallattice sites is responsible for the reduced band gap and improvedtransparency. This work demonstrates a viable method to achieve transparentN-TiO2 films with a visible-light activity, whichcould be useful for various environmental applications such as self-cleaningglass.