Size and Shape Control of Nanocrystallites in Mesoporous TiO2 Films

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We investigated the influences of the titania precursor chemistry and hydrothermal temperature in the sol-gel procedure on the growth of TiO2 nanocrystallites. The nanocrystallites were prepared either from Ti(O iPr)4 (O iPr = isopropoxide) in acetic acid solution or from Ti(O iPr)3(OAc) (OAc = acetate) in water followed by nitric acid acidification. Nanocrystallites formed from the first method were 20-40% larger than those produced from the second method. The average size of calcined TiO2 nanocrystallites formed from Ti(O iPr)4 varied from 16-36 nm over the hydrothermal temperature range of 180-300 °C, while the average size of those prepared from Ti(O iPr)3(OAc) varied from 13-23 nm over temperatures of 200-250 °C. Significantly, the size of the crystallites displayed a linear dependence on the hydrothermal temperature. Crystal growth in acetic acid was enhanced in the [001] direction with increased autoclave temperature, whereas crystallites formed in the presence of nitric acid grew less rapidly in the [001] direction. The mechanisms for the preferential growth direction of the nanocrystals are discussed.

Original languageAmerican English
Pages (from-to)3216-3221
Number of pages6
JournalJournal of Materials Chemistry
Issue number30
StatePublished - 14 Aug 2007

NREL Publication Number

  • NREL/JA-270-41146


  • crystallites
  • mesoporous materials
  • nitric acid
  • sol-gel process
  • thermoanalysis
  • thin films


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