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-??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-?were systematically investgated in visible light irradiation.The main works are showed as follows in this dissertation.?1?Nanoscaled perovskite SrFe_xTi_1-xO_3-?photocatalysts 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-?catalysts 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-?displayed 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-?photocatalysts obeyed pseudo-first-order reaction.Among the prepared catalysts,SrFeO_3-?showed 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-?catalyst 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-?with efficient photocatalytic degradation for these two kinds of dyes.?4?The photoelectrochemical experimental results showed that SrFeO_3-?exhibited higher open-circuit potential and larger photocurrent density than TiO₂,SrTiO_3-?and SrFe_0.5Ti_0.5O_3-?,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-?was 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-?catalysts was proposed via combining the photocatalytic performances and photoelectrochemical results at the end of this dissertation.