Photocatalytic degradation properties of V-doped TiO2 to automobile exhaust.

To improve the photocatalytic degradation properties of titanium dioxide (TiO2) used as raw materials for purifying automobile exhaust (AE), the vanadium (V)-doped TiO2 samples were prepared. The photocatalytic degradation efficiencies of V-doped TiO2 to each component in AE were evaluated under ultraviolet (UV) and visible light irradiation, respectively. Results indicated that the photocatalytic activity of V-doped TiO2 to AE was higher than that of pure TiO2, and the optimal V dopant content of TiO2 was 1.0% under UV light irradiation. The degradation efficiencies of V-doped TiO2 to NOx and HC were higher than those to CO2 and CO in AE because of the reversible reaction between CO2 and CO. In addition, it was found that the photocatalytic degradation efficiencies of V-doped TiO2 to each component in AE were also increased under visible light irradiation. The V-doped TiO2 also showed higher degradation efficiencies to NOx and HC than those to CO2 and CO under visible light irradiation. The V doped TiO2 presented higher photocatalytic activity to CO2 than that to CO, but the reversible reaction between CO and CO2 was not found under visible light irradiation. The photocatalytic reactions of pure and V-doped TiO2 samples to each component in AE followed the first order kinetic pathway under the two light irradiations. It is concluded that the V doping is a feasible method to improve the photocatalytic degradation properties of TiO2 to AE for air purification, developing a sustainable environmental purification technology based on TiO2 materials.