Formation of short In2O3 nanorod Arrays within mesoporous silica

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 degrees 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 similar to 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.