Synthesis of a novel NHTiO2 photocatalyst by annealing in NH3 and H2 for complete decomposition of high concentration benzene under visible light irradiation

• NHTiO2 nanoparticles were prepared by annealing hydrothermally prepared TiO2 in NH3 and H2 for nitrogen doping and hydrogenation.
• The conversion of benzene over NHTiO2 photocatalyst under visible light irradiation was as high as 100% within 3 h.
• The origin of the fundamentally improved performance of NHTiO2 induced by nitrogen doping and hydrogenation was investigated systematically.

A novel NHTiO2 photocatalyst was prepared via hydrothermal synthesis followed by a thermal treatment in NH3 and H2 atmospheres. The results showed that benzene with the initial concentration of 150 ppm (±5 ppm) could be thoroughly removed by NHTiO2 under visible light irradiation. The influences of doping and hydrogenation on properties of TiO2 samples were investigated. It is suggested that the disordered surface layer introduced by hydrogenation contributes to the excellent photocatalytic activity of NHTiO2. The synergistic effect of N doping and surface oxygen vacancies was also confirmed by ultraviolet–visible diffuse reflectance spectra and photoluminescence. Moreover, the diverse role of oxygen vacancies in different positions of TiO2 has been focused on.