Portable and Battery Operated Ammonia Gas Sensor Based on CNTs/rGO/ZnO Nanocomposite

The effect of reduced graphene oxide (rGO) and carbon nanotubes (CNTs) on the gas-sensing performance of ZnO hexagonal nanoparticles, forming CNTs/rGO/ZnO composite has been studied. Samples were obtained by a precipitation route, then characterized by a high resolution transmission electron microscope (HRTEM), x-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis, Raman spectroscopy, Brunauer–Emmett–Teller surface area (BET), and Barrett–Joyner–Halenda (BJH) pore size measurements. The XRD measurements as well as HRTEM confirmed the formation of the hexagonal ZnO nanoparticles over rGO and CNTs. The gas-sensing performance of the synthesized composite are tested toward ammonia gas. Results revealed that, the prepared composite showed good response to ammonia vapor at room temperature with fast response and recovery time. The combined effect of rGO and CNTs played a vital role in enhancing the sensing behavior of an ammonia gas sensor. The obtained sensor was integrated in a simple comparator electronic circuit. The proposed CNTs/rGO/ZnO sensor might give promise for a portable and room temperature ammonia gas sensor.