Highly conductive low-oxygen graphene thin films were produced by thermal annealing of chemically reduced graphene oxide (RGO) sheets under H2 ambient. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy measurements showed that the thermal annealing efficiently removed residual oxygen-containing functional groups on the surface of the chemically reduced RGO sheets and simultaneously recovered sp2 carbon networks in the graphene sheets. Consequently, the electrical conductivity of the graphene films was greatly improved, from 24 S/cm for RGO films to 200 S/cm after the thermal annealing process. In addition, we have studied the NO2 gas sensing characteristics of the prepared graphene films.

Keywords: Graphene, Gas sensors, Annealing.