Graphene oxide synthesis

The method for synthesizing graphene oxide involves several steps, as mentioned in Ref. [⁶⁵]. Firstly, one gram of intercalated graphite was heated in an oven at 900 °C for less than a minute to expand the graphite plates and increase the distance between its sheets. Next, 20 ml of sulfuric acid and two grams of potassium permanganate were mixed using an ice bath. The temperature was then raised to 40 °C, and the expanded graphite was added to the solution and stirred for 2 h using a magnetic stirrer to oxidize the graphite. The resulting paste-like liquid was mixed with 100 ml of cold water and 5 ml of hydrogen peroxide to neutralize the reaction and adjust the pH. The produced material is washed 4–6 times using sodium hydroxide and a high-speed centrifuge to remove impurities. The washed graphite oxide was exfoliated using a high-shear homogenizer. Finally, probe and bath sonication were employed to disperse GO nanosheets and further stabilize them. A schematic view of the synthesis process is shown in Fig. 2. The final product of this step is a GO aqueous dispersion.

Schematic view of GO synthesis process.