Synthesis And Properties Of Graphene @ Ferrite ?TiO₂? Composite Photocatalyst

Spinel ferrites AFe2O4 (A=Ni, Zn, Mn etc.) have attached many attentions for their excellent magnetical and chemical properties and their great potential applications. In recent years, spinel ferrites was studied as a new photocatalyst with narrow band gap due to it can absorb visible light. However, the photocatalytic activity of spinel ferrite is not very high, this limited its development and application. More studies about photocatalyst is focuing on TiO2,but TiO2 only can use of ultraviolet radiation (UV),wihch affects its photocatalytic performance and limits its development. Therefore, modifying TiO2 and ferrites to obtain composite materials, which show better photocatalytic activity, has become a trend.Graphene (GNS) has attracted extraordinary attention for its special crystal structure and exhibits a series of exceptional physical and chemical properties since its discovery in 2004.Herein, we design to deposit AFe2O4 (A=Ni,Zn, Mn) on graphene sheets to prepared graphene@AFe2O4 and use a combination of surfactant and graphene surface active groups,by electrostatic adsorption assembled TiO2 to graphene surface prepared graphene@TiO2 composite materials. The prepared graphene@AFe2O4 (TiO2) composites show large special surface areas introduce by graphene, good photocatalytic activity introduce by TiO2 or AFe2O4 and the magnetic recovery.We synthesized graphene@spinel ferrites AFe2O4 (A=Ni, Zn, Mn) via a low-temperature coprecipitation method. In this process, graphene oxide with a special morphology has been prepared with Hummers method. Then as a raw material, with AFe2O4 (A= Ni, Zn, Mn)aggraded on the graphene nanosheets by a low-temperature coprecipitation method. The mass ratio of graphene and NiFe2O4 in composites can affect the morphologies, photocatalytic performance, and magnetism observably. Interestingly, graphene@NiFe2O4 and graphene@ZnFe2O4 composites show excellent active catalyst under visible light irradiation in the presence of hydrogen peroxide. Graphene@ZnFe2O4 which graphene content less than graphene@NiFe2O4 gave the best performance photocatalytic activity and exhibit excellent magnetic properties. Graphene@MnFe2O4 composites show excellent photocatalytic activity under visible light irradiation in the absence of hydrogen peroxide and excellent magnetic propertiesThe GNS/TiO2 composite materials with different TiO2 content were prepared by antiaddition method. Synthesized GNS/TiO2 have the characteristics of fluffy features and no obvious large particles supported between the graphene sheets. The GNS/TiO2 possess the advantages of the graphene structure,a large number of folds,good dispersion properties. A lot of TiO2 particles can be observed with about 10nm,particles dispersed uniformily. The GNS/TiO2 with difference mass ratio all show high photocatalytic degradation performance for MB under UV irradiation. The sample with TiO2 content of 90% shows the best photocatalytic performance (99%). However, the composite materials have a bad recovery performance from water.The TiO2/GNS/NiFe2O4 composites with different mass ratio were prepared by hydrolysis method. In addition, TiO2/GNS/NiFe2O4 show superparamagnetism at room temperature, which make the composites magnetically separable by additional magnetic field.Reunion phenomenon was observed after TiO2 was wrapped on the particle surface.TiO2/GNS/NiFe2O4 composites can degrade MB under visible-light irradiation,the sample that the mass ratio of TiO2, NiFe2O4 and GNS is 10:1:5 shows the best performance in photocatalytic activity.