A facile approach to synthesize N-doped and oxygen-deficient TiO2 with high visible-light activity for benzene decomposition

N-doped and oxygen-deficient TiO2 photocatalysts were fabricated by a two-step calcination method using dicyandiamide and commercial TiO2 as starting materials. Photocatalytic activity was tested by decomposing gas-phase benzene under visible light irradiation. The nitrogen dopants and oxygen defects in TiO2 played important roles in benzene photodegradation. It was found that the optimum doping dosages of nitrogen and defects (Ti3+/Titotal) were 0.23 wt% and 26 at%, respectively. After photooxidation for 5 h, the benzene conversion rate and CO2 yielded over the as-doped TiO2 were 72% and 190 ppmv, respectively, which were much higher than the sum on NH3-treated TiO2 and H2-treated TiO2. It suggests that the visible-light activity of the modified TiO2 is attributed to a synergistic effect between substitutional N dopants and oxygen defects in TiO2.

► N-doped and oxygen-deficient TiO2 was synthesized by a two-step calcination method using dicyandiamide as a N-containing and reductive reagent.
► Comparative study of NH3-treated TiO2 and H2-treated TiO2 were implemented.
► The sum of the benzene conversion rates or CO2 yields over NH3-treated TiO2 and H2-treated TiO2 was much lower than that on the co-doped catalyst.
► A synergistic effect between N dopants and oxygen vacancies in TiO2 was found.