Facet-dependent decoration of TiO₂ mesocrystals on TiO₂ microcrystals for enhanced photoactivity

Bottom-up constructions of hierarchical TiO₂ are effective to enhance their photoactivity towards degradations of organic pollutants. Thanks to highly active facets, {001} exposed anatase TiO₂ microcrystals attract much attention in photocatalysis; yet their efficiency is limited by the large crystal size. Herein, we report a facile solution approach to deposit anatase TiO₂ mesocrystals only on {101} facets of anatase TiO₂ microcrystals. The selective surface decoration enhances the photoactivity through replacing the less active {101} facets with more active TiO₂ mesocrystals; whilst the highly active {001} facets remain untouched. When utilized to assist photodegradation of phenol in water under UV light illumination, the hierarchical TiO₂ exhibited a reaction rate constant doubled that of the pristine {001} exposed TiO₂ microcrystals. The present tactic to selectively decorate TiO₂ microcrystals may give hints to other applications involving facet-dependent properties. (paper)