The Of Lafeo <sub> 3 </ Sub>-of Tio <sub> 2 </ Sub> Nanocomposite Synthesis And Photocatalytic Performance Study

Nanoscale semiconductors photocatalyst materials have attracted extensive attention of material research and photocatalytic field to resolve the graveness of environment pollution all over the world. Nanosized TiO₂ has developed as a new and very attractive application in photoelectric conversion, heterogeneous photocatalysis materials, due to its unique characteristics. However, the large band energy and low efficience of quatums of nanosized TiO₂, which influenced its performance and restricted its application greatly. Many modify measurements adopted to solve the problems; semiconductor compound is one of the effect methods to enlarge the responce scope of light. And a serial of non-TiO₂ photocatalyst system reaserch such as perovskite is also gradually warming, but, the troditionnal synthsis procedure is one of the factors influencing its activity. Based on the above discussion, to solve the assemble issue, we used the template method to synthesized the perovskite type composite oxides LaFeO₃ in this article, and with the as-prepared LaFeO₃, we prepared the compound LaFeO₃-TiO₂ to solve the large band energy of the nanosized TiO₂.Nanosized LaFeO₃ with large specific surface area has been successfully synthesized by an impregnation process with mesoporous silica SBA-16 as hard template and corresponding metal nitrates as La and Fe resources, and characterized by TG-DTA, XRD, BET, N2 adsorption–desorptions, Raman, SEM, TEM, XPS, Uv-Vis, and SPS. It was found that, compared with that prepared by the conventional citrate method, the as-prepared LaFeO₃ has remarkable large specific surface area, even still with the surface area as large as about 85 m2·g-1 after calcination at 800 oC, which is attributed to its mesoporous structure as well as the small particle size. During the photocatalytic degradation of Rhodamine B solution under visible irradiation, all the LaFeO₃ samples obtained are superior to P25 TiO₂ and the activity becomes high with increasing calcination temperature. It is revealed that the excellent photocatalytic performance is mainly ascribed to the large surface area and high photogenerated charge separation rate. With the as-prepared porous LaFeO₃ with large specific surface area, the compound LaFeO₃-TiO₂ was prepared by the composing of hydrothermal particles and LaFeO₃ particles, the compound materials were characterized by XRD, TEM, Uv-vis DRS, SPS. And the photocatalytic activity of the as-synthesized samples was evaluated by photodegradation of Rhodamine B under irradiation of visible light and Ultra-violet light. The results show that: due to the large specific area and porous structure of LaFeO₃, there is a strong inhibition of phase transition of TiO₂ by a small amount of LaFeO₃; the compound LaFeO₃-TiO₂ not only absorb the Ultra-violet light, but also the visible light which coincided with the photocatalytic activity. The activity of as-synthesized LaFeO₃-TiO₂ compound samples under Ultra-violet light irradiation is higher than the best pure TiO₂ sample, and the activity under visible light irradiation is better than the best pure LaFeO₃ sample, the result is ascribed to the phase composition of the compound LaFeO₃-TiO₂, in which there are anatase, rutile and LaFeO₃ phases, they react with each other when being irradiated under the Ultra-violet or visible light. The way of compounding perovskite and metal oxides has provided a novel method to design and synthesize the high efficiency photocatalyst.