Room temperature detection of NO2 gas under UV irradiation based on Au nanoparticle-decorated porous ZnO nanowires

Abstract

ZnO nanowires were prepared by oxidized ZnS nanowires. The sensing performance of these ZnO nanowires for NO2 gas was enhanced by decorating Au nanoparticles on their surface. The scanning electron microscopy results revealed that diameter and length of the ZnO nanowires showed 150–200 nm and up to a few hundreds of μm, respectively. The diameters of Au nanoparticles which were decorated on the ZnO nanowires were 5–20 nm and they were distributed evenly on the surface of the nanowires. The transmission electron microscopy results revealed that the ZnO nanowires obtained after 2 h of the oxidation treatment process were composed of lots of nanograins with a diameter of 50–100 nm, which rendered the surface of the nanowires rough and full of void spaces. The hierarchical structure of the nanowires increased their surface-to-volume ratio and contributed to the adsorption of gas on their surface, improving their sensing performance. In this study, the NO2 gas sensing mechanism of the Au nanoparticle-decorated ZnO nanowires sensors were investigated under UV illumination at room temperature.