Acidification of La loaded TiO2 for photocatalytic conversion of CO2

Abstract 0.5 M HNO3 acidification of 1.0 wt% La loaded TiO2 photocatalysts with high photocatalytic activity were prepared by sol–gel method and impregnation. The properties of the photocatalysts were characterized by means of SEM, EDS, XRD, HRTEM, BET, XPS, Raman and UV–vis DRS. The results showed acidification and La-doped increased the specific surface area from 28.3 m2/g to 116.9 m2/g of TiO2, promoted the formation of oxygen vacancies and narrowed the band gap to 2.77 eV. The photocatalytic activity of the photocatalysts was tested for photocatalytic conversion of CO2. Acidification of La loaded TiO2 photocatalysts showed 2.9 times higher CH4 yield than pure TiO2 under 4 h visible light irradiation. Furthermore, the acidification of La loaded TiO2 photocatalysts exhibited excellent reusability in four consecutive runs.