Theoretical calculation and experiment study on the electronic structure, microstructures and photocatalytic activity of N–Al codoped TiO2

Abstract

To more accurately demonstrate how the electronic structure was changed by codoping TiO₂ with N–Al and to explain the origin of the enhanced photocatalytic activity by N–Al-codoped TiO₂, we investigated the electronic structures and microstructures of N monodoped, Al monodoped, and N–Al codoped anatase TiO₂ by theoretical calculation and experiments. It was found that N monodoping and Al monodoping could effectively narrow the band gap. The effect was doubled when TiO₂ was codoped with N and Al because the emergence of the N 2p state made the VBM move to a higher energy level and the emergence of the Al 3p state made the CBM move to a lower energy level in the system. Moreover, codoping of N and Al into TiO₂ did not change the microstructures of TiO₂ catalysts although it was proven that both N and Al atoms were codoped into TiO₂. N and Al-codoped TiO₂ displayed a higher crystallinity and a higher specific surface area than others. According to the results about the degradation rate and the dynamics of the catalysts, N–Al–TiO₂ exhibited the best photocatalytic activity; this suggested that N and Al were combined to enhance the photocatalytic activity of TiO₂.