F修饰对SiO2@TiO2亲疏水性及光催化性能的影响

采用两步法制备了氟修饰疏水性F-SiO_2@TiO_2材料.以三乙氧基氟硅烷(TEFS)为硅源,采用后嫁接的方法在短孔道MCM-41小球表面引入F原子,再利用醇热法在F-MCM-41小球表面生长TiO_2纳米晶颗粒.利用透射电子显微镜(TEM)、X射线粉末散射(XRD)、X射线光电子能谱(XPS)、N_2气吸脱附等手段表征了材料的物相组成和表面结构.研究表明:所制备的氟修饰F-SiO_2@TiO_2纳米复合材料为核壳结构,具有较大的比表面积、较好的介孔结构及较佳的热稳定性.同时,TiO_2纳米颗粒在F-MCM-41小球表面分散均匀、结晶度高、颗粒尺寸小且均一、与F-SiO_2结合牢固.重量吸附实验和光催化实验进一步证实F修饰可抑制水的吸附有利于提高F-SiO_2@TiO_2材料的疏水性和对气相有机污染物的光催化性能.

The effect of fluorine modification on hydrophilic-hydrophobic properties and photocatalytic performance of SiO2@TiO2 hybrids

Hydrophobic fluorine modified SiO₂@TiO₂ hybrids were prepared by a post-grafting method followed by a solvothermal method.F-SiO₂ precursor was firstly prepared via a simple post-grafting process using triethoxyfluorosilane as a fluorine-containing silylation agent.Then,nano-sized TiO₂ particles were formed on the surface of F-SiO₂ to form F-SiO₂@TiO₂ by a solvothermal process.Different characterizations were performed to show the detailed structure of F-SiO₂@TiO₂ hybrids such as TEM,XRD,XPS and N₂ adsorption-desorption etc.The results show that F-SiO₂@TiO₂ hybrids with core-shell structure own large surface area,well-ordered mesoporous structure as well as high thermostability.On the other hand,the well dispersed TiO₂ particles with small and similar size display high crystallinity and strong interaction with F-SiO₂.Both the adsorption and the photocatalytic experiments toward degradation of organic compounds show that increasing the content of TEFS reagent could suppress the adsorption of H₂O on the surface of F-SiO₂@TiO₂ hybrid.As a result,the F-SiO₂@TiO₂ samples display higher hydrophobic properties and higher photocatalytic activities than SiO₂@TiO₂ sample.