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Mesoporous Anatase Titania Hollow Nanostructures though Silica‐Protected Calcination
Author(s) -
Joo Ji Bong,
Zhang Qiao,
Lee Ilkeun,
Dahl Michael,
Zaera Francisco,
Yin Yadong
Publication year - 2012
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201101927
Subject(s) - anatase , materials science , calcination , chemical engineering , crystallinity , mesoporous material , amorphous solid , photocatalysis , crystallization , nanotechnology , composite material , organic chemistry , catalysis , chemistry , engineering
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.