Comparative study of deoxygenation behavior for graphene oxide with different oxidation degree and mildly reduced graphene oxide via solid-state microwave irradiation

The influence of the oxidation degree of graphene oxide (GO) on its deoxygenation efficiency via hybrid microwave heating (HWH) method by using graphite powder as the external susceptor was investigated, and the response behavior was compared with the situation when GO is directly submitted to microwave irradiation. In addition, the deoxygenation behavior of mildly reduced GO (VRGO) that was obtained via chemical reduction by Vitamin C was compared with that of GO during above two microwave heating processes. No response of GO to microwave irradiation when GO samples are exposed directly to microwave, no matter how the oxidation degree is. However, the VRGO sample can be heated when it is solely submitted to microwave irradiation. The partial reduction of GO leads to enhancement of the dielectric parameters, and the residual defects and oxygen-containing functional groups not only can improve the impedance matching characteristics, but also produce defects polarization relaxation and dipole polarization relaxation, which are all beneficial to the microwave penetration and absorption. The deoxygenation efficiency of VRGO is lower in comparison with GO under the HWH condition, which should be attributed to higher amount of epoxides in GO samples that can be easily reduced in a mixed heating mode. [Display omitted] •Hybrid microwave heating (HWH) is a effective approach to reduce graphene oxide (GO).•The lower oxidation degree of GO has higher deoxygenation efficiency via HWH.•No response of GO with low oxidation degree when it is exposed directly to microwave.•Chemically pre-reduced GO can be heated when it is solely submitted to microwave.•The partial reduction of GO leads to the enhancement of microwave absorption ability.