ZnO Nanorod Arrays and Hollow Spheres through a Facile Room-Temperature Solution Route and Their Enhanced Ethanol Gas-Sensing Properties

A new two-phase solution strategy has been developed for the synthesis of multifarious zinc oxide one-dimensional (1D) nanostructures, in which nanorod arrays (NAs), nanorod hollow spheres (NHSs), nanoribbons, nanowires, nanotubes, and nanonetworks were easily obtained at room temperature without using any catalysts, templates, or precursors. More importantly, an interesting formation mechanism of the 1D nanostructures in the benzene/water system and its distinctive size- and morphology-controlling ability were also discovered. Through a series of directed comparison experiments, it was found that the zinc source, reactant concentration, substrate, and reaction time played significant roles in this dipolar binary liquid technique. In addition, and considering their importance to semiconductor ZnO gas-sensing properties, the energy state and surface status of the as-obtained NA and NHS products were investigated through photoluminescence and surface wetting measurements. It was found that a large concentration of oxygen vacancies and high surface energy were present on the surface of the NAs and NHSs, which resulted in their enhanced ethanol gas-sensing properties at a relatively low temperature.