Preparation And Properties Of G-ZnFe₂O₄ Nanocomposite

Steadily worsening environmental pollution have raised awareness of a potential global crisis. Human survival and society face serious chanllenge of water pollution. Photocatalysis processes advantages of normal temperature reaction, green energy, degradability strong and advantages of cleaning thoroughly, becoming the emerging technology. The structure of photocatalyst plays an important role in photocatalytic performance.We synthesized the G-ZnFe₂O₄ through microwave thermal treatment, respectively.USGO acts as barriers for the confined growth of ZnFe₂O₄ nanocrystals. The microstructure and morphology of the prepared materials were examined by the X-ray diffraction （XRD）,scanning electron microscopy （SEM）, transmission electronic microscopy （TEM）, BET and so on. The relationship of photocatalytic performances, structure and preparation were also discussed in detail. Specific steps are as follows:First of all, we report a novel strategy for spatially confined growth of ZnFe₂O₄ within graphene network through microwave thermal treatment and find both of them have synergstic effect. G-ZnFe₂O₄-500 has ultrasmall cubic nanoparticles with the sizes of about 20nm, which is far smaller than ZnFe₂O₄-500 （50 nm）. The graphene network formed by USGO is beneficial for larger surface area and fast electron transport, resulting in the enhanced photocatalytic performances.Then we discuss the influence of annealing temperatures on the photocatalytic performance and microstructure. In this dissertation, the G-ZnFe₂O₄ nanocomposite as photocatalyst was prepared at different annealing temperatures. The microstructure and morphology of the prepared materials were also examined. Wih temperature increasing, the surface area, nanoparticle size and photocatalytic performances of ZnFe₂O₄ decrease obviously. Moreover,it can be clearly seen that the activity of G-ZnFe₂O₄ continually increases with temperature increasing from 300 to 500℃ due to the enhanced degree of crystallinity. The interconnected graphene network in the hybrid is beneficial for spatially confined growth of ZnFe₂O₄ and fast transport of photon-excited electron from catalyst surface,resulting in high photocatalytic activity. As a result, ZnFe₂O₄ nanocrystals with highly crystallized （311） plane confined in the graphene network exhibit an excellent visible-light-driven photocatalytic activity, much higher than ZnFe₂O₄ photocatalysts.Finally, we discuss the influence of carbon support on the photocatalytic performance and microstructure. In this paper, we compare the microstructure and photocatalytic performance of G-GO-ZnFe₂O₄ with G-ZnFe₂O₄, GO-ZnFe₂O₄ and ZnFe₂O₄. Among them,G-GO-ZnFe₂O₄ was synthesized with graphene as a conductive carbon substrate and USGO as conductive barriers. The size of G-GO-ZnFe₂O₄ nanocrystals is 10 nm, exhibiting a high photocatalytic ability and adsorption. In addition, we prove that the size of G-ZnFe₂O₄ nanoparticles becomes larger due to the increasing size of USGO.