Preparation, characterization and visible light photocatalytic activity of nitrogen-doped TiO2

The N-doped TiO2 polycrystalline powder was synthesized through calcining the hydrolysis product of tetra-butyl titanate with ammonia. The photocatalytic activity of N-doped TiO2 powder with anatase phase calcined at 400°C was 2.7 times higher than that of Degussa P25 for phenol decomposition under visible light. All samples had mesoporous structures. X-ray photoelectron spectroscopy confirmed that a trace amount of N atoms remained in the anatase polycrystalline TiO2 powder when calcined at 400°C as substitutional atoms at the oxygen sites. UV-Vis and EPR analyses indicated that oxygen vacancy states were created during the course of N-doped TiO2 powder formation. It is considered that substitutional N atoms, oxygen vacancy states, large BET surface areas and mesoporous structure are important factors for the N-doped photocatalyst to present a high vis-activity.