Synthesis, Characterization, and Nitrogen Concentration Depended Visible-Light Photoactivity of Nitrogen-Doped TiO2 Nanosheets with Dominant (001) Facets

Abstract

Anatase TiO2 nanosheets with dominant (001) facets were prepared by a simple hydrothermal method. Nitrogen-doped TiO2 nanosheets (TiO2-N) with different nitrogen concentration were successfully synthesized by annealing TiO2 nanosheets in NH3 atmosphere with different NH3 flow rate at 400 °C for 3 h. The morphology, nanostructures, and properties of TiO2-N were characterized by X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence. The effects of NH3 flow rate on the nanostructures, properties, and visible-light photoactivity in the degradation of rhodamine B (RhB) aqueous solution under visible light (λ> 400 nm) irradiation of the prepared photocatalysts were investigated. Among all the prepared photocatalysts including nitrogen modified P25 (Degussa), TiO2-N prepared with a NH3 flow rate of 40 ml/min gave the highest visible-light photoactivity because of the dominant (001) facets, visible light responsibility, the slowest photogenerated electron (e−) and hole (h+) pairs recombination rate, and the highest hydroxyl radicle (·OH) generation ability. Based on these experiments and analysis, the mechanisms of how the nitrogen concentration affects the visible-light photoactivity of TiO2-N were proposed.