Laser-assisted hydrothermal growth of size-controlled ZnO nanorods for sensing applications.

Pulsed laser irradiation is used to seed the low-temperature hydrothermal growth of ZnO nanorods. UV laser irradiation produces ZnO nanoparticles in solution that act as nucleation seeds for the subsequent hydrothermal growth of the nanorods. By systematically varying the seed density and/or the concentration of the reactants, the diameter of the nanorods can be controlled over a wide range with a narrow size distribution. The nanorods are linked into multi-pod structures, due to nucleation at a central seed, but ultrasonic processing of the solutions is shown to yield isolated nanorods. Three-dimensional networks of these multi-pod structures are fabricated by drop-casting the solutions onto inter-digitated electrodes. These devices are used to detect ethanol, water vapour and UV light exposure.