Preferential growth of long ZnO nanowires and its application in gas sensor

Long single crystalline ZnO nanowires with an average diameter of 50 nm and lengths of up to 9 μm were synthesized by a sudden hydrothermal reaction of Zn(NO3)2·6H2O aqueous solution and NaOH aqueous solution. The formation mechanism of the long ZnO nanowires was studied in detail. In addition, Au nanoparticles were introduced on the surface of ZnO nanowires using a wet-chemical reduction method. Both the long ZnO nanowires and Au-nanoparticle-functionalized ZnO nanowires (Au NPs-ZnO NWs) were applied to fabricate gas sensors for the detection of some organic vapors. The as-fabricated gas sensors exhibit high gas-sensing response, and short response and recovery time. Compared with the ZnO nanowires, the Au NPs-ZnO NWs exhibit a higher response and lower working temperature to some organic vapors, such as ethanol and n-butanol. Such behaviors can be attributed to catalytic activity of Au nanoparticles and Schottky contact at the Au/ZnO interface.