目的 构筑具有尺寸选择性光催化功能的复合纳米结构，在维持二氧化钛材料光催化性能的同时，减少其对有机大分子材料及有机基底材料的腐蚀行为，拓宽光催化材料的使用范围。方法 采用一锅法，通过TEOS围绕P25为核进行水解，制备了多孔SiO2包覆TiO2（P25）复合核壳结构（P25@SiO2）纳米颗粒。结果TEM、XRD、BET表征显示，这种复合核壳纳米结构具有较好的分散性和很高的比表面积（约528 m2/g）。光催化性能实验证实，这种复合核壳结构具有尺寸选择性光催化效应，即小分子氮氧化物气体（NOx）能通过壳层SiO2孔道进入核层并降解90%以上，被氧化成硝酸盐固定下来；小分子有机物亚甲基蓝能穿过壳层孔道进入复合结构的核层部分，被氧化分解；大分子有机物胭脂红被壳层有效隔离而不被分解。老化试验显示，涂覆有这种核壳结构材料的有机基材（PET膜）被氧化老化的现象受到抑制。相反，与裸露的有机基材（PET膜）相比，由于壳层的保护作用，涂覆有核壳纳米结构的有机基材具有更好的抗紫外线性能。结论 开发的这种具有尺寸选择性光催化的复合核壳结构材料，可以涂覆在各种有机基材的表面，赋予其一定的光催化功能，同时由于壳层的隔离保护作用，对基材的腐蚀作用受到抑制。这种复合核壳纳米结构也可以作为功能添加材料添加到各种涂料材料中，并赋予涂料一定的光催化性能，同时对涂料中的有机物不会产生强烈的分解作用，因此具有很好的应用前景。

The work aims to fabricate a composite nanostructures featuring in size selective photocatalytic function, which can maintain photocatalytic property of TiO2, and reduce the photocatalytic corrosion behavior to organic macromolecular materials and organic substrates, so as to expand range of application of photocatalytic materials. One-pot method was used to hydrolyze with P25 as core by means of TEOS and prepare porous TiO2 (P25) nano-particles in composite core-shell nanostructure (P25@SiO2) covered by SiO2. TEM, XRD and BET tests verified that the P25@SiO2 exhibited good dispersion and high specific surface area (about 528 m2/g). Photocatalytic performance test confirmed that this core-shell composite had a size selective photocatalytic effect, i.e., small molecule nitrogen oxide gas (NOx) could enter TiO2 core through SiO2 shell pore passage and further was decomposed by over 90%; a small molecule organic methylene blue could also penetrate into the core parts through SiO2 shell pore passage and was oxidized and thereby decomposed, while macromolecular organic Ponceau 4R was effectively insulated and was not decomposed. The aging experiments showed that organic substrate PET membrane coated with P25@SiO2 was not restrained by oxidization and ageing. On the contrary, compared with the bare organic substrate PET membrane, the organic substrate coated with core-shell nanostructure had better UV resistance due to protective effect of the shell layer. The size selective photocatalytic composite core-shell material can be coated on the surface of various organic substrates, providing them with certain catalytic function. Meanwhile, owing to the protective effect of SiO2 shell, the corrosive effect on substrate is inhibited. In addition, the core-shell materials can be added in various coating materials as function addition material, endowing coatings with photocatalytic properties such as air purification and self-cleaning function without damaging some organic compounds in the coatings. Therefore, the P25@SiO2 materials have very good application prospects.