Investigation of Effective Parameters in Improving the Yield of Graphene Produced by Supercritical Fluids

Supercritical carbon dioxide (scCO2) has the remarkable ability to penetrate graphite layers with significant force and low viscosity, effectively overcoming Van der Waals (VdW) forces and converting graphite into mono/bilayer graphene. By utilizing data from Design Expert software (version 7.0) and conducting laboratory experiments, it has been demonstrated that various parameters such as temperature (T), pressure (P), initial amount of graphite, surfactant and co-solvent addition, duration of sample placement in the cell, CO2 gas release duration, ultrasonic and centrifuge operation time, and power can significantly enhance the exfoliation process. The graphene produced was meticulously analyzed using advanced techniques such as RAMAN spectroscopy, High Resolution Transmission Electron Microscopy (HRTEM), Fourier Transform InfraRed (FT-IR) spectroscopy, Zeta potential analysis, and Atomic Force Microscopy (AFM). The results conclusively showed that under optimal conditions, mono/bilayer graphene was successfully achieved. This was confirmed by the presence of the G-Band at 1581 cm-1 in the RAMAN spectroscopy. The HRTEM images clearly displayed the formation of graphene layers under the applied conditions, while FT-IR results indicated that graphene sheets were successfully synthesized after applying appropriate conditions, with a thickness of 1.49 nm as observed in the AFM. The zeta potential value for this nanofluid was measured at -39.7 mV, indicating excellent stability. This innovative method offers a straightforward and cost-effective approach that eliminates the need for toxic or expensive chemicals, positioning it as a highly lucrative alternative to more complex graphene production methods, such as heating silicon carbide.