Study on gas sensing of reduced graphene oxide/ZnO thin film at room temperature

We report the synthesis, characterization and gas sensing performance of reduced graphene oxide (RGO) and RGO/ZnO bilayer thin films prepared by facile sol-airbrush technology at room temperature. We found that RGO/ZnO bilayer films exhibit enhanced surface roughness and more spacing compared to RGO. Sensing performance measurements showed that RGO/ZnO film has 30% enhancement of Delta R/R-0 to chloroform vapor compared to pure RGO film due to the improvement of film structure. A slight enhancement of AR/R-0 was also observed on exposure to other vapors (water, ethanol, acetone and formaldehyde), with response and recovery time less than 10s. To explore the stability of RGO film, we studied the effect of various flow rates of background gas on the electric resistance variation. It was found that electric resistance fell at a larger flow rate, rose at a smaller rate, and Delta R/R-0 became smaller after annealing. These results can be understood by the air pressure-induced deformation of RGO film. We further proposed a new method to calculate the sensing response, which was verified to be more reliable for sensing performance analysis with negligible hysteresis. We expect these findings to shed new light on future development of high-performance gas sensors based on bilayer films. (C) 2016 Elsevier B.V. All rights reserved.