Web Release Date: January 26,
Formation of Short In2O3 Nanorod Arrays Within Mesoporous Silica
Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
Received: October 16, 2007
In Final Form: December 3, 2007
Abstract:
We report the formation of arrays of short In2O3 nanorods inside of the nanoscale channels of mesoporous
silica SBA-15. In(NO3)3 dissolved in methanol was incorporated into the SBA-15 powder, followed by heat
treatment under a nitrogen flow at 700 
C for 4 h to generate densely aligned In2O3 nanorods. The nanorods
have been characterized by XRD patterns, TEM images, nitrogen adsorption-desorption isotherm measurements, and optical spectroscopy. They possess a cubic In2O3 crystal structure. The free-standing In2O3 nanorods
obtained after silica framework removal with a 2.0 M NaOH solution showed diameters of 6-7 nm and
lengths of largely less than 50 nm. Some nanorods can be as short as less than 10 nm in length. The nanorods
exhibit an absorption band at ~300 nm. The observation of this quantum-confined effect is likely induced by
the small nanorod diameter. A fluorescence peak centered at 387 nm was recorded. No other oxygen-vacancy-related emission signals in the blue to green light region were present, suggesting a high crystalline quality
of the short In2O3 nanorods synthesized.
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