Ultrasonic Processing of Hierarchically Organized TiO2 Functional Nanomaterials

Abstract

Hierarchically organized functional nanomaterials are of interest for potential use in electrochemical, catalytic and gas-sensing applications due to their unique structural organization defined on different length scales. Here we present the application of the aerosol processing route in generation of hierarchically organized nanostructured TiO2 particles. Particles are obtained by the thermal decomposition of aerosol generated by atomization of colloidal TiO2 solution with a low-intensity ultrasound generator operating at the high frequency of 1.7 MHz. By a proper choice of the precursors type and concentration, as well as processing parameters (temperature of aerosol decomposition and the residence time of droplet/particle), fine control over both the submicron- and nanometer-length scales of spherically structured TiO2 was achieved. The median diameter and the crystallite size of titania particles were found to be tunable from 350 to 450 nm and from 2.5 to 50 nm, respectively. Moreover, it was shown that the structural complexity of the particles synthesized at the lower processing temperatures might be further extended by their surface sensitization with several bidentate ligands. The results obtained demonstrate advantages of ultrasonic spray pyrolysis route in synthesis of hierarchically organized functional nanomaterials.