Preparation, photocatalytic performance and electronic structures of visible-light-driven Fe–N-codoped TiO2 nanoparticles

Fe–N-codoped TiO2 powder prepared by sol–gel method is loaded on low-density polyethylene film to obtain immobilized photocatalyst. The obvious agglomeration phenomena exist in the annealed samples with nanometer size, as observed in SEM images. XRD results suggest that the adding amount of impurities has a great effect on the crystallinity and particle size of TiO2. Compared with undoped and Fe/N-doped TiO2, Fe–N-codoped TiO2 shows an obviously higher catalytic activity under visible irradiation. The DFT calculations indicate that the doping of nitrogen and Fe induced the formation of new states between the valence band and conduction band. The codoping of TiO2 with nitrogen and Fe leads to the much narrowing of the band gap and greatly improves the photocatalytic activity under visible irradiation. Moreover, the Fe–N-codoping can promote the separation of the photogenerated electrons and holes to accelerate the transmission of photocurrent carrier.