A systematic study on visible-light N-doped TiO2 photocatalyst obtained from ethylenediamine by sol–gel method

•N-doped titania with a higher N-doping level is prepared by a sol–gel method.•Doping mechanism is explained by XRD, FT-IR and UV–visible absorption spectroscopy.•Photocatalytic performance is evaluated by dye degradation and H2 evolution. N-doped titania is prepared using ethylenediamine as the nitrogen source by a sol–gel method. The preparation conditions, such as the volume ratio of ethylenediamine to sol, and the heat temperature on the nitrogen doping are systematically examined. UV results indicate the N-doped TiO2 catalysts have enhanced absorption in the visible light region, and exhibit high activities on the visible light photocatalytic reactions to the hydrogen production and methyl orange degradation. X-ray diffraction (XRD) and FT-IR results reveal that N species have been incorporated into the TiO2 lattice at a high N-doping level. N-doped titania prepared with an ethylenediamine to sol volume ratio of 1:1 and sintering temperature of 500°C performed the highest hydrogen production rate (2.98mmolg−1h−1) and best methyl orange degradation performance. A conceivable structure change of N-doped TiO2 sintered at different temperature was proposed.