Preparation And Degradation Performance Of Hollow CeO₂@TiO₂/RGO Composite Photocatalyst

With the gradual development of industrialization,the problem of environmental pollution has become more serious.Among the many methods of treatment,photocatalytic technology has received widespread attention because it can effectively degrade pollutants and has no secondary pollution.Photocatalysts mainly play a catalytic role in photocatalysts,among which TiO₂ is one of the most studied semiconductor photocatalysts because of its good photocatalytic properties and stable properties.However,TiO₂ also has two defects as photocatalysts.First,due to the wide bandgap,it can only be excited by ultraviolet light during photocatalytic reaction,and does not respond to visible light basically;second,the electrons generated after the semiconductor is excited are easily recombined with holes in the transfer process,so their use in real life is still greatly limited.Therefore,it is necessary to find other novel photocatalysts with excellent properties or to improve the defects existing in TiO₂ semiconductors.CeO₂ with excellent oxygen storage capacity and lower bandgap allow it to have a certain ability to respond to visible light,and its practical application as a photocatalyst is broader.After the composite of CeO₂ and TiO₂ forms a heterojunction interface,the bandgap width of the composite material decreases,and the response to visible light is significantly improved compared to a single semiconductor.It has been found that hollow-core-shell nanomaterials have a high specific surface area and can better utilize incident light through mutual reflection between the core and the shell.In addition,the combination of the semiconductor photocatalytic material and the graphene can utilize the good conductive properties of the graphene to rapidly transfer the photogenerated electrons on the semiconductor conduction band to prevent recombination with the photogenerated holes.In order to investigate the photocatalytic properties of CeO₂@TiO₂?@is coated?after the composite CeO₂ with TiO₂,and the photocatalytic efficiency of the CeO₂@TiO₂/RGO?/is composite?composite modified with graphene?RGO?.In this paper,TiO₂ hollow spheres,CeO₂ hollow spheres,hollow-core-shell CeO₂@TiO₂ microspheres,and hollow-core-shell CeO₂@TiO₂/RGO microspheres with different graphene additions were synthesized.XRD,SEM,FT-IR,XPS and other advanced detection techniques were used to test the phase composition and morphology of the prepared materials.And discussed their synthesis mechanism,the ability of degradation of Rhodamine B solution and the photocatalytic mechanism.The specific research content and conclusions of this article are as follows:?1?A carbon microsphere template,graphene oxide?GO?was first prepared for use.Using carbon microsphere template and precipitation-hydrothermal method,TiO₂hollow spheres,CeO₂ hollow spheres and CeO₂@TiO₂ microspheres with hollow-core-shell structure were prepared.Then,the surface of CeO₂@TiO₂microspheres was aminated,and CeO₂@TiO₂ was combined with graphene oxide with different mass ratios through amide groups to obtain CeO₂@TiO₂/GO.Then,graphene oxide was hydrothermally reduced to graphene.Finally,CeO₂@TiO₂/RGO nanospheres with different graphene additions were obtained.?2?Through the scanning electron microscopy image of the material,it can be seen that a carbon microsphere template with a spherical structure was successfully prepared,but the particle size of the template was not uniform and there was a certain degree of agglomeration;TiO₂ microspheres and CeO₂ microspheres with a hollow structure were synthesized;CeO₂@TiO₂ nanospheres with a hollow-core-shell structure successfully composited;the filamentous graphene on the surface of CeO₂@TiO₂ microspheres were successfully synthesized.?3?From the XPS spectrum of the material,the Ti-O-C bond is formed between the graphene and the outer shell titanium dioxide,indicating that the coating process is chemical coating;the C 1s spectrum of the material can further illustrate that the graphene oxide in CeO₂@TiO₂/RGO compound was successfully reduced.?4?By analyzing the fluorescence spectrum of the material,the fluorescence intensity of CeO₂@TiO₂ was decreased after the composite of CeO₂ and TiO₂,which showed that the heterojunction formed by the semiconductor composite can reduce the recombination rate of the photogenerated electron-hole pair of the material.After adding graphene,the fluorescence intensity of CeO₂@TiO₂/RGO was lower than that of CeO₂@TiO₂,indicating that the outermost coated graphene can promote the separation of photoelectron-hole pairs.?5?The UV-Vis spectrophotometer was used to test the degradation efficiency of photodegradation of rhodamine B solution under ultraviolet light?different light intensity?and simulated sunlight.The results show that the photocatalytic efficiency of CeO₂@TiO₂ is significantly higher than that of single shell CeO₂ and TiO₂,both under UV and simulated sunlight conditions;after adding graphene,the CeO₂@TiO₂/RGO composite is comparable to CeO₂@TiO₂,the degradation efficiency of Rhodamine B is increased by about 10%,and the optimal addition amount of graphene is 3 wt%.