Formation of Short In2O3 Nanorod Arrays Within Mesoporous Silica

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,...