Preparation, Photocatalytic Activity, and Mechanism of Nano-TiO₂ Co-Doped with Nitrogen and Iron (III)

Nanoparticles of titanium dioxide co-doped with nitrogen and iron (III) were first prepared using the homogeneous precipitation-hydrothermal method. The structure and properties of the co-doped were studied by XRD, XPS, Raman, FL, and UV-diffuse reflectance spectra. By analyzing the structures and photocatalytic activities of the undoped and nitrogen and/or Fe3+-doped TiO2 under ultraviolet and visible light irradiation, the probable mechanism of co-doped particles was investigated. It is presumed that the nitrogen and Fe3+ ion doping induced the formation of new states closed to the valence band and conduction band, respectively. The co-operation of the nitrogen and Fe3+ ion leads to the much narrowing of the band gap and greatly improves the photocatalytic activity in the visible light region. Meanwhile, the co-doping can also promote the separation of the photogenerated electrons and holes to accelerate the transmission of photocurrent carrier. The photocatalyst co-doped with nitrogen and 0.5% Fe3+ shows the best photocatalytic activity, the degradation efficiencies of which were improved by 75% and 5% under visible and ultraviolet irradiation, respectively, compared with the pure titania.