摘要
Mesoporous nanocrystal clusters of anatase TiO2 with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the self-assembly of hydrophobic TiO2 nanocrystals into submicron clusters, coating of these clusters with a silica layer, thermal treatment to remove organic ligands and improve the crystallinity of the clusters, and finally removing silica to expose the mesoporous catalysts. With the help of the silica coating, the clusters not only maintain their small grain size but also keep their mesoporous structure after calcination at high temperatures （with BET surface area as high as 277 m2/g）. The etching of SiO2 also results in the clusters having high dispersity in water. We have been able to identify the optimal calcination temperature to produce TiO2 nanocrystal clusters that possess both high crystallinity and large surface area, and therefore show excellent catalytic efficiency in the decomposition of organic molecules under illumination by UV light. Convenient doping with nitrogen converts these nanocrystal clusters into active photocatalysts in both visible light and natural sunlight. The strategy of forming well-defined mesoporous clusters using nanocrystals promises a versatile and useful method for designing photocatalysts with enhanced activity and stability.
有大表面区域和提高的 photocatalytic 活动的锐钛矿 TiO2 的 Mesoporous nanocrystal 簇成功地被综合了。合成包含进亚微米簇，有硅石层的这些簇的涂层，移开器官的 ligands 并且改进簇的 crystallinity 的热处理，和暴露 mesoporous 催化剂的最后搬迁的硅石的恐水病的 TiO2 nanocrystals 自己组装。在硅石涂层的帮助下，簇不仅维持他们的小谷物尺寸而且在高温度在锻烧以后保留他们的 mesoporous 结构(与象 277 m2/g 一样高的赌注表面区域) 。蚀刻 SiO2 也导致在水里有高 dispersity 的簇。我们能识别最佳的锻烧温度生产拥有高 crystallinity 和大表面区域的 TiO2 nanocrystal 簇，因此由紫外光在照明下面在器官的分子的分解显示出优秀催化效率。与氮的方便的做在可见的光和自然日光把这些 nanocrystal 簇变换成活跃光催化剂。用 nanocrystals 形成明确的 mesoporous 簇的策略为与提高的活动和稳定性设计光催化剂答应一个万用、有用的方法。
