Preparation Of Graphene Oxide-based Nanocomposites And Their Application In Trace Detection And Photocatalysis Of Dyes

Functional composite nanomaterials is the frontiers and hot spots in materials science research.It is also an important carrier in the field of practical application of nanomaterials.Graphene oxide based functional composites have demonstrated promising applications in the fields of energy,electronics,biomedicine,catalysis and environmental pollution treatment et al.This paper aims to design graphene oxide based functional composite nanomaterials to realize the trace detection and catalytic degradation of dyes.Considering the fact taht graphene oxide is easy to agglomerate and difficult to separate in application,we use the SiO₂ microspheres with large specific surface area as the carrier of GO.In the field of dye trace detection,we design and preparated the Fe₃O₄@SiO₂-GO@Ag composite material,which can effectively enrich the target molecule in the dye solution,combined with SERS technique realizes the identification and analysis of trace multicomponent contaminants.For the catalytic degradation of dyes,we designed and fabricated the SiO₂@GO-TiO₂ composite nanomaterials for the photocatalytic degradation of dye.Real time SERS spectroscopy was used to monitor the surface catalytic degradation process of the composite,and the recycling performance of the material was verified.From the perspective of SERS application,the material is also a kind of a multifunctional SERS substrate with the function of self cleaning.The main work of this paper is divided into three parts:1.The Fe₃O₄@SiO₂-GO and SiO₂@GO-TiO₂ nanocomposites were prepared by selfassembly method.Taking Fe₃O₄@SiO₂-GO as an example,after fabricating the Fe₃O₄ magnetic nanoparticles by solvothermal method,we coated it with a layer of SiO₂ coating by the Stober method.Following with the surface amino functionlization,the nano particles were self assembled on the graphene oxide to form the Fe₃O₄@SiO₂-GO nano composite particles by electrostatic interaction.The transmission electron microscopy（TEM）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）,vibrating sample magnetometer（VSM）,zeta potential characterization results show that the Fe₃O₄@SiO₂-GO nanocomposite particles were successfully prepared.The preparation process of SiO₂@GO-TiO₂ nano composite particles is same as above.2.The adsorption mechanism of dyes on Fe₃O₄@SiO₂-GO and its application in SERS trace analysis were studied.Taking the methylene blue（MB）,crystal violet（CV）as the targets,the effects of the pH and initial concentration of the samples solution,the amount of adsorbent,and the contact time were investigated by batch process and the adsorption mechanism were obtained.After the enrichment of silver nanoparticles,the composite showed excellent SERS sensitivity.The detection limits respectively reached 1×10^-7M（MB）,1×10^-10M（CV）and can be realized the simultaneous trace detection of dye molecules in the mixed solution.Compared with other analytical methods,establishing a rapid SERS analysis technology of dyes which is suitable for the rapid response of environmental pollution scene makes sense in environmental emergency and environmental monitoring.3.Study on the photocatalytic degradation of SiO₂@GO-TiO₂ in xenon lamp simulating sunlight environment,and we used real time SERS spectroscopy to monitor the surface catalytic degradation process.The results show that the graphene oxide can not only enrich the dye molecules,but also can improve the separation efficiency of photogenerated charge in TiO₂ due to the excellent electronic properties,which further improve the photocatalytic efficiency.In addition,the material can be separated from the system at a low rate of centrifugation,and can be reused for at least 3 times.From the perspective of SERS application,we also get a kind of efficient,low cost and reuseable SERS substrate.