The Photocatalytic Properties Of Strontium Titanate Ferrite Semiconductor Materials In Visible-light Irradiation

Due to the advantages of low cost,environment friendness and high efficiency,solar light-driven semiconductor-based photocatalysis is an important research subject in organic pollutants degradation with great practical application values.By reviewing the synthesis methods of semiconductor-based photocatalysts and photocatalytic degradation mechanism,here perovskite SrFe_xTi_1-xO_3-δ（x=0,0.1,…,1）photocatalysts were prepared via high energy ball milling for degradation of methylene blue in aqueous solution.Meanwhile,the photocatalytic degradation performances of SrFe_xTi_1-xO_3-δwere systematically investgated in visible light irradiation.The main works are showed as follows in this dissertation.（1）Nanoscaled perovskite SrFe_xTi_1-xO_3-δphotocatalysts were successfully synthesized via high energy ball milling with average size less than 20 nm.The introduction of Fe ion at B site in perovskite structure generated additional valence and conduction bands in the badgap of SrTiO₃,resulting in a redshift of the adsorption threshold wavelength and enhanced its visible response.（2）The photocatalytic performances of prepared SrFe_xTi_1-xO_3-δcatalysts were investgated by visible light-induced degradation of MB at room temperature.Compared to anatase TiO₂,all prepared catalysts exhibited higher visible light photocatalytic activity,in which SrFeO_3-δdisplayed the best catalytic performance with degradation ratio of98.585%.Kinetics sutdy demonstrated that the degradation of MB in presence of SrFe_x Ti_1-xO_3-δphotocatalysts obeyed pseudo-first-order reaction.Among the prepared catalysts,SrFeO_3-δshowed the largest apparent reaction rate constant(0.25038 h^-1),which was 3.23 times of TiO₂ under the same conditions.（3）The effects of light source,solution pH value,photocatalyst dosage and initial MB concentration were systematically investgated for photocatalytic degradation with SrFeO_3-δcatalyst in aqueous suspension.The optimal conditons were confirmed as 300 W halogen lamp,pH=10,the catalyst dosage of 0.2 g,and the initial MB concentration of 10 mg/L.Moreover,the visible light-induced photocatalytic degradation of MO demonstrated SrFeO_3-δwith efficient photocatalytic degradation for these two kinds of dyes.（4）The photoelectrochemical experimental results showed that SrFeO_3-δexhibited higher open-circuit potential and larger photocurrent density than TiO₂,SrTiO_3-δand SrFe_0.5Ti_0.5O_3-δ,indicating the efficient separation of photogenerated electron-hole pairs,which was in accordance with the photocatalytic performances.Combined with flat band potential experimental results,it can be concluded that the high photocatalytic activity of SrFeO_3-δwas the synergistic effects originating from the narrowing of the band gap and the reduction of the band-edge potential.（5）The visible light-induced photocatalytic degradation mechanism of MB with SrFe_xTi_1-xO_3-δcatalysts was proposed via combining the photocatalytic performances and photoelectrochemical results at the end of this dissertation.