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

Abstract

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/cm². 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.