Transparent Nb-doped TiO films with the [001] preferred orientation for efficient photocatalytic oxidation performance.

Doping and tailoring of the crystal orientation are two main strategies to improve the photocatalytic properties of TiO films. Herein, we introduce a novel route for obtaining Nb-doped TiO anatase films with the [001] preferred orientation by thermal oxidation of the [100]-oriented Nb-doped TiN film prepared by magnetron sputtering. Comprehensive analyses with X-ray diffraction, Raman scattering, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy indicate that the proportion of high-energy (001) facets of the Nb-doped TiO film is more than 90% and the Nb ion is successfully doped into the film without destroying the crystallinity and orientation. Moreover, the Nb ion doping significantly restrains the growth of the TiO grains and increases the surface roughness, and consequently increases the surface-reactive sites. Therefore, the as-fabricated Nb-doped TiO film exhibits efficient photocatalytic oxidation performance for acetaldehyde and oleic acid decomposition under simulated solar light irradiation. Such Nb-doped TiO anatase films with high-reactivity (001) facet exposure may find applications in the photocatalysis and solar energy conversion fields.