Growth, characterization and investigation of gas-sensing performance of graphene and copper-doped zinc oxide prepared by sol-gel method

Pure zinc oxide, graphene-, copper- and copper/graphene-doped zinc oxide samples were synthesized by the sol-gel technique. The sol-gel prepared samples have been studied by X-ray diffraction, field-emission scanning electron microscopy and Fourier transform infrared spectroscopy. The gas-sensing performance of the samples was examined through an electric circuit towards different vapours (i.e., ethanol, methanol, acetone and isopropanol). It was observed that the sensitivity was affected by graphene and copper. The main ethanol sensing features of the samples were measured and compared with each other. The sensitivity and the time of response and recovery of the sensing material were commonly improved after doping. Based on the results, the doped samples had a more acceptable status than the ZnO sample and particularly, the sample with both graphene and copper had a peculiar attitude due to sensitivity enhancement and response/recovery time reduction. The copper/graphene-doped zinc oxide can be a good replacement for a pure zinc oxide gas sensor.