水基纳米TiO_2路径制备有序介孔TiO_2-SiO_2及其可见光催化性能

在多巴胺修饰的水基TiO_2纳米微粒(TiO_2NPs)悬浮液中,以正硅酸乙酯为硅源,十六烷基三甲基溴化铵为模板剂,分别采用碱性水热方法或酸性溶胶-凝胶方法,制备了有序介孔TiO_2-SiO_2(TiO_2NPs/MCM-41或TiO_2NPs/SBA-3)。采用XRD、TEM、ICP和N2吸附-脱附实验对样品进行表征。结果表明,制备的介孔TiO_2-SiO_2在TiO_2高负载质量分数(23.98%TiO_2NPs/MCM-41、17.27%TiO_2NPs/SBA-3)时,仍能保持长程有序的介孔氧化硅结构。TiO_2NPs随机地嵌入在有序介孔氧化硅孔道所组成的网络结构中。在可见光下催化甲基橙降解反应中,反应时间120 min时,在P25上甲基橙相对浓度降为57%,在TiO_2NPs/MCM-41上降为33%,而在TiO_2NPs/SBA-3上降为5.7%。

Preparation of ordered mesoporous TiO2-SiO2 by a water-based TiO2 nanoparticle route and its visible photocatalytic activity

Using cetyltrimethyl ammonium bromide as template and tetraethyl orthosilicate(TEOS) as silicon source,ordered mesoporous TiO₂-SiO₂ composites(TiO₂NPs/MCM-41 or TiO₂NPs/SBA-3) were synthesized in dopamine-modified water-based TiO₂ nanoparticles(TiO₂NPs) suspension by basic hydrothermal synthesis procedure or acidic sol-gel method.The mesoporous TiO₂-SiO₂ composites were characterized by small- and wide-angle XRD,TEM,ICP and nitrogen adsorption-desorption experiments.The results showed that the synthetic samples still maintained highly ordered mesoporous silica structure even with high TiO₂ loading mass fraction of 23.98% and 17.27% for TiO₂NPs/MCM-41 and TiO₂NPs/SBA-3,respectively.TiO₂NPs were randomly embedded in framework of the mesoporous silica channels.In the photocatalytic degradation of methyl orange under visible light irradiation for reaction time 120 min,the relative concentration value(C/C₀) of methyl orange was reduced to 57%,33% and 5.7% over P25,TiO₂NPs/MCM-41 and TiO₂NPs/SBA-3,respectively.