In-situ transmission electron microscopy (TEM) investigation of the reduction process in graphene oxide

The reduction processes of graphene oxide (GO) aim to remove functional groups such as H2O, CO, and CO2 to promote the properties of GO towards those of pure graphene. We adopted the thermal reduction process from room temperature to 320 °C. The transmission electron microscopy (TEM) technique was used to probe the effect of reduction mechanisms. It was observed that the plasmon peaks, referring to sp2 carbon bonds in crystalline structures, are more evident in the reduced graphene oxide (rGO) than GO. The fine structure at the K edge of carbon shows differences in shape linked to the density of states above the Fermi level. Electron energy loss spectroscopy (EELS) analyses revealed an increase in the fraction of sp3 bonds in the reduced sample, consistent with the reduction of functional radicals in the GO structure.