Mesoporous Anatase Titania Hollow Nanostructures though Silica‐Protected Calcination

Abstract

Abstract The crystallization of nanometer‐scale materials during high‐temperature calcination can be controlled by a thin layer of surface coating. Here, a novel silica‐protected calcination process for preparing mesoporous hollow TiO 2 nanostructures with a high surface area and a controllable crystallinity is presented. This method involves the preparation of uniform silica colloidal templates, sequential deposition of TiO 2 and then SiO 2 layers through sol–gel processes, calcination to transform amorphous TiO 2 to crystalline anatase, and finally etching of the inner and outer silica to produce mesoporous anatase TiO 2 shells. The silica‐protected calcination step allows crystallization of the amorphous TiO 2 layer into anatase nanocrystals, while simultaneously limiting the growth of anatase grains to within several nanometers, eventually producing mesoporous anatase shells with a high surface area (∼311 m 2 g −1 ) and good water dispersibility upon chemical etching of the silica. When used as photocatalysts for the degradation of Rhodamine B under UV irradiation, the as‐synthesized mesoporous anatase shells show significantly enhanced photocatalytic activity with greater enhancement for samples calcined at higher temperatures thanks to their improved crystallinity.