Improvement of gas sensing behavior in reduced graphene oxides by electron-beam irradiation

We first report the mechanism of gas sensing improvement of reduced graphene oxides (RGOs) by electron-beam irradiation. We have irradiated the RGO samples by the electron beam with doses of 100 and 500 kGy. Raman spectra indicated that electron-beam irradiation generates defects. X-ray diffraction and X-ray photoelectron spectroscopy and initial resistance data consistently suggest that oxygen functional groups were increased by the electron-beam irradiation, with them being decreased by increasing the dose from 100 to 500 kGy. By the sensing test with respect to NO₂ gas, we revealed that the NO₂ response was increased not only by the electron-beam irradiation but also by increasing the electron dose. We revealed that the mechanism of the electron-beam-induced improvement of gas sensing behavior was dependent on the amount of electron dose. While the oxygen functional groups are likely to play a key role in enhancing the adsorption behavior of NO ₂ molecules in case of 100-kGy irradiation, further sensing enhancement at 500-kGy irradiation originates from the non-oxygen defects. The results suggest that the electron-beam irradiation can be a useful tool to turn the RGOs into more favorable sensing materials.