Hydrothermally grown oriented ZnO nanorod arrays for gas sensing applications

C-axis vertically aligned ZnO nanorod arrays were synthesized on a ZnO thin film through a simple hydrothermal route. The nanorods have a diameter of 30-100 nm and a length of about several hundred nanometres. The gas sensor fabricated from ZnO nanorod arrays showed a high sensitivity to H-2 from room temperature to a maximum sensitivity at 250 degrees C and a detection limit of 20 ppm. In addition, the ZnO gas sensor also exhibited excellent responses to NH3 and CO exposure. Our results demonstrate that the hydrothermally grown vertically aligned ZnO nanorod arrays are very promising for the fabrication of cost effective and high performance gas sensors.