▎ 摘　　要

In this paper, we report that graphene nanosheets (graphene)/polyaniline (PANI) nanocomposite with a different mass ratio of graphene to PANI are synthesized and applied to fabricate methane (CH4) sensor. The experimental results show that the sensitivity of the graphene/PANI sensor with the composite thin film, which can be obtained by a chemical or physical method, is higher than that of PANI. Meanwhile, the sensitivity of the sensors on the basis of graphene/PANI composite by an in situ chemical method is higher than the sensitivity of those produced by a physical mixing method. The possible reason is that the graphene/PANI compounds have higher surface area than that of PANI. In addition, the detection range of the sensor is enlarged by increasing the mass ratio of graphene to PANI. We infer that there exists a pi-pi* conjugation system within the graphene/PANI and then use it to explain the above result. The samples are characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively.