耐高温核/壳结构TiO2/SiO2复合气凝胶的制备及其光催化性能

以钛酸四丁酯为源, 采用苯胺-丙酮原位生成水溶胶-凝胶法, 在乙醇超临界干燥过程中用部分水解的钛醇盐和硅醇盐对TiO₂凝胶进行超临界修饰制备了具有核/壳纳米结构的块体TiO₂/SiO₂复合气凝胶. 制备的复合气凝胶具有优异的机械性能, 其杨氏模量可达4.5 MPa. 复合气凝胶同时具有极好的高温热稳定性. 经过1000 ℃热处理后, 线性收缩由纯TiO₂气凝胶的31%降至复合气凝胶的10%, 且比表面积由纯TiO₂气凝胶的31 m²·g^-1提升至复合气凝胶的143 m²·g^-1. 此外, 该复合气凝胶经1000 ℃热处理后具有优异的光催化降解亚甲基蓝的性能. 其优异的光催化性能得益于TiO₂/SiO₂复合气凝胶1000 ℃处理后高的比表面积和小的颗粒尺寸. 优良的耐热性能、力学性能和光催化性能使获得的具有核/壳纳米结构的TiO₂/SiO₂复合气凝胶在光催化领域具有良好的应用前景.

Preparation of Heat-Resistant,Core/Shell Nanostructured TiO2/SiO2 Composite Aerogels and Their Photocatalytic Properties

Core/shell nanostructured monolithic TiO₂/SiO₂ composite aerogels were prepared by the anilineacetone in situ water formation sol-gel method. Titanium(IV) n-butoxide was used as a precursor followed by supercritical modification with partially hydrolyzed titanium alkoxide and tetraethoxysilane during ethanol supercritical fluid drying. The obtained composite aerogel showed excellent mechanical strength with a Young's modulus of 4.5 MPa. The composite aerogel exhibited excellent heat resistance. After heat treatment at 1000 ℃ its linear shrinkage decreased from 31% for the TiO₂ aerogel to 10% for the composite aerogel. The specific surface area increased from 31 m² ·g^-1 for the TiO₂ aerogel to 143 m² ·g^-1 for the composite aerogel. The composite aerogel exhibited excellent photocatalytic performance during the degradation of methylene blue after heat treatment at 1000 ℃. Its excellent photocatalytic property is attributed to its high specific surface area and the small particle size of the composite aerogel after heat treatment at 1000 ℃. The enhanced heat resistance, mechanical strength, and photocatalytic performance makes the obtained core/shell nanostructured TiO₂/SiO₂ composite aerogel a promising candidate for photocatalytic applications.