Light-activated NO2 gas sensing of the networked CuO-decorated ZnS nanowire gas sensor

CuO-decorated ZnS nanowires were synthesized by the thermal evaporation of ZnS powders followed by a solvothermal process for CuO decoration. The NO2 gas sensing properties of multiple-networked pristine and CuO-decorated ZnS nanowire sensors were then examined. The diameters of the CuO nanoparticles ranged from 20 to 60 nm. The multiple-networked pristine and CuO-decorated ZnS nanowire sensors showed the responses of 394 and 1055 %, respectively, to 5 ppm of NO2 at room temperature under UV illumination at 2.2 mW/cm(2). The response and recovery times of the ZnS nanowire sensor to 5 ppm of NO2 were also reduced by decoration with the CuO nanoparticles. The responses of the sensors to NO2 at room temperature increased significantly with increasing UV illumination intensity. The underlying mechanisms for the enhanced response of the ZnS nanowire sensor to NO2 gas by CuO decoration and UV irradiation are discussed.