摘要：Mesoporous nanocrystal.clusters of anatase TiO2 with l.rge surface area and enhanced photocatal.tic activity have been successful.y synthesized. The synthesis invol.es the sel.-assembl. of hydrophobic TiO2 nanocrystal. into submicron clusters, coating of these clusters with a sil.ca l.yer, thermal.treatment to remove organic l.gands and improve the crystal.inity of the clusters, and final.y removing sil.ca to expose the mesoporous catal.sts. With the hel. of the sil.ca coating, the clusters not onl. maintain their smal. grain size but al.o keep their mesoporous structure after cal.ination at high temperatures （with BET surface area as high as 277 m2/g）. The etching of SiO2 al.o resul.s in the clusters having high dispersity in water. We have been abl. to identify the optimal.cal.ination temperature to produce TiO2 nanocrystal.clusters that possess both high crystal.inity and l.rge surface area, and therefore show excel.ent catal.tic efficiency in the decomposition of organic mol.cul.s under il.0}mination by UV l.ght. Convenient doping with nitrogen converts these nanocrystal.clusters into active photocatal.sts in both visibl. l.ght and natural.sunl.ght. The strategy of forming wel.-defined mesoporous clusters using nanocrystal. promises a versatil. and useful.method for designing photocatal.sts with enhanced activity and stabil.ty.