Monolithic TiO2 with controlled multiscale porosity via a template-free sol-gel process accompanied by phase separation
Monolithic TiO2 with controlled multiscale porosity via a template-free sol-gel process accompanied by phase separation
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DOI：
10.1021/cm0617485
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发表时间：
2006-12-12
影响因子：
8.6
通讯作者：
Hirao, Kazuyuki
中科院分区：
文献类型：
--
作者：
Konishi, Junko;Fujita, Koji;Hirao, Kazuyuki
本文介绍了在无模板条件下，采用溶胶-凝胶法和相分离相结合的一步法制备多尺度多孔纳米二氧化钛单体的方法。在钛醇盐的水解和缩聚反应中，通过控制溶液的pH值，自发地获得了具有良好大孔和中孔结构的锐钛矿型TiO2凝胶骨架的大尺寸整体。通过起始成分调整大孔的大小，无需热处理即可形成晶化的锐钛矿型二氧化钛骨架。醇钛的使用通过在缩合反应中形成化学键来加强凝胶网络，得到的多孔整体比使用冷冻干燥的胶体二氧化钛制备的多孔整体具有更高的机械强度，以保持多孔形态。结果表明，干凝胶中锐钛矿型纳米粒子的平均尺寸约为3.6 nm，300℃下焙烧的凝胶中锐钛矿型纳米粒子的平均尺寸约为5.0 nm。高比表面积(类似于150m(2)/g)即使在300℃热处理后仍保持不变。
This article describes the fabrication of multiscale porous nanocrystalline TiO2 monoliths through a one-step method that combines a sol-gel process and phase separation in template-free conditions. A large-dimension monolith with well-defined macropores and a mesostructured anatase-type TiO2 gel skeleton is spontaneously obtained by controlling the solution pH during the hydrolysis and polycondensation reactions of titanium alkoxides. The size of the macropores is adjusted by the starting composition, and a crystallized anatase TiO2 skeleton is formed without heat treatment. The use of titanium alkoxide strengthens the gel network by the formation of chemical bonding in the condensation reaction, which yields porous monoliths with higher mechanical strength than for the case of porous monoliths derived from colloidal TiO2 using freeze drying to maintain the porous morphology. The average crystallite size of anatase TiO2 nanocrystals was found to be about 3.6 nm for the dried gel and about 5.0 nm for the gel calcined at 300 degrees C. As a result of the growth of the anatase TiO2 nanoparticles, the mesopores with a median size of 5.0 nm are obtained. The high surface area (similar to 150 m(2)/g) is maintained even after the heat treatment at 300 degrees C.