A comparative study for producing few-layer graphene sheets via electrochemical and microwave-assisted exfoliation from graphite powder

Graphene's astonishing properties drew attention of many scientists to dedicate a lot of their time to find out more about this extraordinary material. However, challenges continue to produce high-quality graphene in large quantities by using inexpensive and readily available methods. In this study, three different graphite powders have been used as starting materials to produce few-layer graphene sheets, which are pure natural graphite (NGr) and two different electrochemically treated expanded graphite EE1 and EE2. Two simple and time-effective techniques have been applied on the samples interchangeably to investigate the order effect on producing graphene sheets in few-layer form. These techniques are sonication in dimethylformamide (DMF) for one hour and rapid microwave irradiation for 30 s. The study suggests that if the graphite powder is treated first with a strong exfoliation reagent followed by microwave irradiation, the obtained graphene will be high-quality few-layer (similar to 5 layers). Sonication in DMF has worked to increase the inter-planar spacing between graphite layers, while microwave irradiation has worked to decrease the defect density ratio that resulted after sonication process. Our work suggests a novel route to prepare high-quality few-layer graphene sheets, not only with time efficiency, low-cost, and without using harmful chemicals, but also an adequate method for large-scale high-efficiency production of graphene materials.