Gas discrimination by ZnO nanowire arrays with different metal oxide coatings

Three-dimensional (3D) metal oxide nanowire arrays have large surface area and numerous gas transport channels, which can significantly improve the gas sensing performance, such as sensitivity, response and recovery speed, etc. compared to their thin films counterparts. Furthermore, different metal oxide coatings can be used to diversify the chemical reactivity of the nanowires for gas discrimination. A general route to polycrystalline metal oxide nanowire array has been introduced by using ZnO nanowire arrays as structural templates. Two different metal oxide coatings (CuO and SnO₂) have been applied onto the ZnO nanowire arrays to modify the gas sensing properties. The polycrystalline metal oxide coatings showed high performance for gas detection. The electronic nose system consisted of these two types of gas sensors can discriminate air-diluted NO₂ and H₂S.