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 NO2 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.