Preparation And Photocatalytic Activity Of Tio₂-sio₂ System Metamaterial

Titanium dioxide(TiO2)is an important inorganic functional material.The combination of SiO2 and TiO2 help to obtain TiO2-SiO2 composites with various morphologies.In photocatalysis,it can benefit for a better photocatalytic property.However,due to its own structure and properties,TiO2 has a low utilization rate of light.That limits photocatalytic effect of TiO2.At present,it is one of the effective ways to improve the photocatalytic performance of TiO2-SiO2 composite materials thorough changing composite forms.On the other hand,photonic crystals have the characteristics of interfering with the behavior of photons because of the special morphological characteristics.Introducing photonic crystal structure into photocatalytic materials can effectively improve the absorption and utilization of light.And thus,it can improve their photocatalytic performance.In this paper,using titanium trichloride as the titanium source,sodium lauryl sulfate as an additive,and deionized water as the solvent,SiO2-TiO2 hetero-composite structure thin films were successfully fabricated on SiO2 inverse opal structure film.Using polystyrene colloidal photonic crystal as a template,TiO2-SiO2 inverse opal structure was prepared by TiO2-SiO2 composite precursor which was obtained by a sol-gel method.Using the SiO2 inverse opal structure as a framework,the SiO2 inverse opal framework@TiO2-SiO2 composite structure was prepared by a sol-gel method.Multiple testing methods were used to characterize the micro-morphology,crystal phase and absorption spectrum of the samples.The characterization and mechanism of the photocatalytic performance were analyzed using Rhodamine B(Rh B)as the simulated pollutants.This process is used to simulate photocatalytic degradation of pollutants in real environment.The effects of different process factors on the photocatalytic performance of SiO2-TiO2 hetero-composite thin films were analyzed.The influences of polystyrene photonic crystal templates,calcination temperature and other factors on the photocatalytic performance of TiO2-SiO2 inverse opal structure were studied.The effects of the size of inverse opal structure and calcination temperature on the photocatalytic property of the SiO2 inverse opal framework@TiO2-SiO2 composite structure were investigated.And the photocatalytic mechanism of different system materials was explored.The main results are shown follows:(1)Combining SiO2 inverse opal structure film with hydrothermal method,SiO2-TiO2 hetero-composite composite structure films with different morphological characteristics were successfully prepared.By controlling the reaction conditions,the formation process of the heterogeneous composite structure film was explored.When the hydrothermal temperature was 180? and the hydrothermal time was 2 h,the degradation rate of Rh B of the prepared sample can achieve 88.22%with 30 minutes reaction of a small amount of TiO2 under UV light irradiation.The improvement of the photocatalytic performance is attributed to the porous concave structure obtained by the growth.And the morphology of the composite effectively promotes the exchange of reactive materials and improves the light utilization of the film.(2)By controlling the preparation temperature of polystyrene microspheres,colloidal microspheres with different particle sizes were prepared,and then TiO2-SiO2 inverse opal structure powders with different pore sizes were prepared by the sol-gel method.The combination of TiO2-SiO2 and photonic crystals effectively improves the agglomeration of the composite powders and increases its utilization of the space.When the pore size of the TiO2-SiO2 inverse opal structure is between 130 nm and 190 nm,the photocatalytic performance of the powders can be effectively improved.When the pore size is too small,the decrease in strength makes it difficult to construct the inverse opal structure and the mismatch between the theoretical photonic band gap position and its electronic band gap,which leads to the weakened photocatalytic performance.(3)Using the SiO2 inverse opal structure as the framework,the SiO2 inverse opal framework@TiO2-SiO2 composite structure with good adsorption performance and catalytic performance was successfully obtained via the sol-gel method.By controlling the pore size of the SiO2 inverse opal structure,calcination temperature,calcination time and other factors,composite products with good three-dimensional ordered porous structures can be obtained.The SiO2 inverse opal framework@TiO2-SiO2 composite structure not only has outstanding adsorption performance of the SiO2 inverse opal structure,but also has the good photocatalytic property of TiO2-SiO2 composite,which greatly accelerates the degradation efficiency of the pollutants.In addition,the inverse opal structure can effectively reduce the agglomeration of the powder and improve the utilization of light.