A solvothermal method for growing ZnO nanostructures with different morphologies is presented. Nanowires, nanorods, nanocorns, nanoshuttles, nanoworms, and nanoflowers with excellent crystallinity have been successfully fabricated by combining two different coordination agents and adjusting the ratio of solvents and the reaction time. The nanowires and nanorods are of high aspect ratio (>500 and 50, respectively) and exhibit a perfect single crystalline wurtzite structure. The growth process responsible for the variation in morphology is discussed.

Well-defined single crystalline TiO 2 nanowires with diameters of 20-50 nm mostly and lengths of up to a few millimeters have been successfully synthesized by a simple, low-cost solvothermal process using the mixed solvent aqueous NaOH-ethanol. The as-synthesized nanowires are structurally uniform, of high purity and show perfect crystallinity. The growth mechanism of the nanowires has been investigated by following the growth steps of the samples at various reaction stages. The solvent significantly influences the morphology and the crystallization behavior of the final products. This novel approach may be applied to the large-scale fabrication of some other oxide nanowires.

TiO2 thin film based, chemiresistive sensors for NO2 gas which operate at room temperature under ultraviolet (UV) illumination have been demonstrated in this work. The rf-sputter deposited and post-annealed TiO2 thin films have been characterized by atomic force microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction to obtain surface morphology, chemical state, and crystal structure, respectively. UV-vis absorption spectroscopy and Tauc plots show the optical properties of the TiO2 films. Under UV illumination, the NO2 sensing performance of the TiO2 films shows a reversible change in resistance at room-temperature. The observed change in electrical resistivity can be explained by the modulation of surface-adsorbed oxygen. This work is the first demonstration of a facile TiO2 sensor for NO2 analyte that operates at room-temperature under UV illumination.