Preparation and properties of anatase - rutile mixed crystal Fe-TiO2 with high catalytic activity under visible light

Abstract

With the development of society, water pollution is becoming more and more serious, especially dyeing wastewater. Fe-doped TiO2 nano-photocatalyst was prepared by hydrothermal method. The crystal structure, morphology, optical properties, band gap width (Eg) and photocatalytic properties of the synthesized nanoparticles were characterized by XRD, SEM, TEM, EDS, XPS, FT-IR and UV–vis. The results show that Fe-TiO2 is a mixed crystal form of rutile type and anatase type, the average crystal diameter of anatase type is 11 nm, and the diameter of rutile type is 10–50 nm. The addition of Fe can effectively reduce the band gap width of TiO2 from 3.22 eV to 2.33 eV, so as to expand the visible light absorption range. Under 350 W xenon lamp irradiation, the degradation rate of Rhodamine B (RhB) reached 95.3% with 2% Fe-TiO2 nanoparticles in the synergistic effect of sodium persulfate (PS) for 40 min, and the nanoparticles had good reusability. Free radical quenching experiments showed that·OH, SO4-·, e-, and h+ pairs favored RhB degradation. The addition of Fe can form additional energy levels in TiO2, so that the smaller energy photons can excite the electrons and holes trapped in the additional energy levels, so that the absorption of TiO2 is redshifted and the visible light absorption range is extended. Meanwhile, PS accelerates the transformation between Fe(Ⅲ) and Fe(Ⅱ), thereby effectively improving the photocatalytic efficiency.