Formation and trapping of CO2 due to the decomposition of amide solvents during the chemical reduction of graphene oxide by using the solvothermal method

Abstract

We report on the chemical reduction (cR) of graphene oxide (GO) by the solvothermal method at 180 °C using two similar amide solvents, dimethylformamide (DMF) and dimethylacetamide (DMA). One of the differences between the obtained cRGO nanostructures is their solubility in polar solvents. This can be related to the quantity of decomposed amide molecules into carbon monoxide (CO), a reducing agent, and amine molecules of the employed solvents. The amount of reactive agent generated with DMA during the solvothermal reduction process is lower than those resulting from the use of DMF. Thus, a large (small) quantity of oxygen groups in GO sheets is removed using DMF (DMA) as reducing agent. The removal of oxygen groups from GO sheets, due to interaction with CO, creates CO2 molecules and some of them are trapped between cRGO nanocrystals. Despite vacancy creations in graphene sheets, via CO2, the average size of GO sheets is preserved during the reduction process, indicating the tendency of CO to heal vacancies in the graphene lattice. Moreover, different GO concentrations have been used to study the reduction efficiency of these solvents. Average sizes of cRGO sheets as well as their graphitization are similar for both solvents, showing that the influence of GO concentrations in the cRGO crystallinity is limited.