Research On Photocatalytic Performance Of Titanium Dioxide Hollow Spheres Simultaneously Sensitized With Valence Band And Conduction Band

The TiO2 hollow sphere structure belongs to the category of zero-dimensional materials in the spatial dimension.The structural advantages increase the available surface area and the rate of mass transfer for adsorbate.In addition,In addition,energy can be effectively utilized,which makes it widely used in many fields such as photocatalysis,solar cells and photolysis water.However,based on the defects of TiO2 itself,on the one hand,it can only be excited under ultraviolet light due to the wide forbidden band width;on the other hand,the photogenerated electrons and holes on the surface are easily recombined and the lifetime of carrier is low.Currently,the main solutions to the above problems include doping,compound semiconductor,control active surface and surface sensitization etc.Among these methods,only doping and surface sensitization can directly perform photocatalytic reaction under visible light.However,there are certain defects in doping.Although surface sensitization allows the catalyst to be excited under visible light,it is mainly a single sensitization method that only sensitizes the TiO2 conduction band and its effect is limited,the advantages of TiO2 cannot be fully utilized.Based on this,we propose a double sensitization idea,that is,the conduction band and the valence band of TiO2 are respectively sensitized by two kinds of semiconductors,so that the photocatalytic reaction is carried out on the surface of TiO2 and the advantages of TiO2 are fully exerted.In this paper,the three-sensitized TiO2 hollow spheres of three systems were prepared by template hydrothermal method,kinetic coating method with ammonia controled and photodeposition method,and the system was further optimized and its photocatalytic performance was tested.The results are as follows:(1)In a short period of time,the photocatalytic performance of the three systems of double-sensitized TiO2 hollow spheres is better than that of single-sensitized TiO2 hollow spheres.With the process of photocatalytic reaction,the photocatalytic performance is inhibited,By introducing Pt into the system to.Optimize the structure,it can promote the separation of electrons and holes on WO3.(2)The optimized double-sensitized TiO2 hollow sphere was used for photocatalytic performance test.It was found that its photocatalytic performance was significantly improved and its degradation mechanism was studied.That is,Pt promotes the separation of electrons and holes in WO3,WO3 and CdS respectively sensitize the valence band and conduction band of TiO2,which leads to the system directly performing excitation under visible light.(3)A series of samples with different gradients were prepared by changing the photodeposition time and controlling the amount of sodium tungstate added,and their photocatalytic performance were tested.The obtained rules were explained and the best performance samples were obtained.It was also found that when 1 g of sodium tungstate was added and the photodeposition time was controlled at 1.5 h,the sample has excellent photocatalytic performance.