Selective Growth of ZnO Nanorods and Its Gas Sensor Application

The facile sonochemical method has been used to selectively grow a ZnO nanorods sensing layer directly on an alumina substrate. The growth region of the ZnO nanorods array is precisely controlled by a pre-coated Pt/Zn seed layer on alumina substrate. No growth of ZnO nanostructure is found on the substrate without seed layer. The grown ZnO nanorods are well aligned and densely packed, with wurtzite crystal structure and flat hexagonal tip. The sensing properties of the obtained ZnO nanorods sensing layer to three kinds of toxic gases ( NH₃, CO, and CH₄) have been investigated. The sensing observation revealed that the selectively grown ZnO nanorods demonstrated good response, repeatability, and excellent linearity toward toxic gases. This result indicates that selective growth of ZnO nanorods directly on sensor substrate is an accessible and advantageous method for sensor fabrication.