UV-Enhanced Acetone Gas Sensing of Co3O4-Decorated ZnS Nanorod Gas Sensors

Co3O4-decorated ZnS nanorods were synthesized by the thermal evaporation of ZnS powders followed by a sol-gel process for Co3O4-decoration. The acetone gas sensing properties of multiple-networked pristine and Co3O4-decorated ZnS nanorod sensors were examined. The diameters of the Co3O4 nanoparticles ranged from 4 to 20 nm. The multiple networked pristine ZnS nanorods and Co3O4-decorated ZnS nanorod sensors showed responses of 156 - 364% and 198 - 1,650% to 10 - 500 ppm of acetone at room temperature under UV illumination at 2.2 mW/cm(2), respectively. The response and recovery times of the ZnS nanorod sensor at 500 ppm of acetone was reduced from 52 s to 26 s and from 192 s to 110 s, respectively, by Co3O4-decoration. The responses of the sensors exhibited strong dependence on the UV illumination intensity. The responses of the pristine ZnS nanorod and Co3O4-decorated ZnS nanorod sensors to 500 ppm of acetone at room temperature increased from 112 to 364% and from 132 to 1650%, respectively. This paper discusses the underlying mechanisms of the enhanced response of the ZnS nanorod sensor to acetone gas by Co3O4-decoration and UV irradiation.