三维多孔SiO_2-TiO_2异质结材料的制备及其光催化性能

Preparation of Three-Dimensional Multiporous SiO_2-TiO_2 Heterojunction Composites and Their Photocatalytic Performance

在锐钛矿相TiO2纳米晶基础上,通过溶胶-凝胶法,以聚甲基丙烯酸甲酯(PMMA)微球为模板合成了三维(3D)多孔SiO2-TiO2异质结复合材料,采用XRD、ESEM等技术对产物进行表征,并研究了其光催化特性.结果表明:复合SiO2提高了纳米锐钛矿相TiO2的亲水性,经550℃热处理后的TiO2仍具有以锐钛矿相为主的相组成;在光催化降解甲基橙实验过程中,经去模板后形成的三维多孔SiO2-TiO2异质结复合材料表现出较纯锐钛型TiO2更为优异的光催化活性,其降解速率较TiO2提高了3倍,较SiO2提高了30倍,这主要与复合SiO2后其锐钛矿相结晶度提高和三维多孔结构具有更大的比表面积等因素有关.

Three-dimensional （3D） multiporous SiO2-TiO2 heterojunction composites were synthesized on the base of the pure anatase TiO2 nanocrystals by a sol-gel method using the polymenthyl rnethacrylate （PMMA） microspheres as a tem- plate. The products were characterized by X-ray diffraction （XRD）, environmental scanning electron microscopy techniques （ESEM）, and then the photocatalytic properties were studied. The results show that the composited SiO2 can improve the hydrophily of nano-anatase TiO2, and the composite of SiOz-TiOz keeps a principal anatase phase composition after being heat-treated at 550 ℃. During the experimental process of the photocatalytic degradation of methyl orange, the as-above three-dimensional （3D） multiporous SiO2-TiO2 heterojunction composites exhibit higher activity than pure anatase TiO2 pre- pared by moving template at high temperature, the decomposition rate of methyl orange solution is improved to be 3 times higher than the rate by pure nano-anatase TiQ, and 30 times higher than the rate by SiO2, it is attributed to the high anatase crystallinity and the large surface area of 3D multiporous microstructure after SiO2 is doped.