IMPROVEMENT OF SENSITIVE CHARACTERISTICS AT ROOM TEMPERATURE OF NH3 GAS SENSOR BASED ON COMPOSITE OF NANO CARBON AND ZnO NANOPARTICLES
Abstract
Due to the necessity to have NH3 gas sensors with good gas-sensitivity properties, operating at room temperature, we fabricated the resistive sensor based on ZnO and nano carbon (carbon nanotubes - CNT, graphene oxide - GO) composite. In which, CNT was synthesized by chemical vapor deposition, GO was synthesized by Hummers’s method, and ZnO was synthesized by sol-gel method. The structures of the pure and composite materials were investigated by field emission scanning electron microscopy and Raman spectroscopy. The NH3 sensitivity of the sensors to the proportions of the composites was investigated a concentration of 60 ppm. The results show that the sensors based on composite have a higher response than the pure materials. In particular, the sensor based on the CNT/GO/ZnO composite had the best response that was 17.3%, and the response time and recovery time are significantly improved respectively by 40s and 70s. The gas-sensitization mechanism based on the p-n transition between carbon nanomaterials and ZnO is responsible for enhancing the gas-sensitivity characteristics of composite-based sensors.