Graphene is an unconventional material with a two-dimensional hexagonal crystalline array of elemental carbon atoms and outstanding properties; accordingly, a desirable objective in the line of research of graphene is the development of novel and more productive methods of synthesis, validating its properties and applications. In our exploratory research, we have effectively exfoliated graphene from graphite using supercritical fluids (water, ethanol and carbon dioxide). The exfoliated graphene was properly characterized; via scanning electron microscopy, the morphology of graphene was observed; Raman spectra confirmed the exfoliation of graphene depicting the characteristic shift towards smaller Raman number in the 2D band (2676 cm−1) compared to that of graphite (≈ 2700 cm−1); transmission electron microscopy analysis exhibited the crystalline structure of graphene attesting also the expected transparency of exfoliated layers. Graphene exfoliation from graphite by supercritical fluids promises to be a simple large-scale method for graphene production.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Materials
        2.2 Supercritical exfoliation of graphene
        2.3 Supercritical water and supercritical ethanol exfoliation experiments
        2.4 Supercritical CO2 exfoliation experiments
        2.5 Characterization
    3 Results and discussion
    4 Conclusions
    Acknowledgements 
    References

• Rodolfo Morales Ibarra(Faculty of Mechanical and Electrical Engineering, Universidad Autónoma de Nuevo León, Av. Universidad S/N, Ciudad Universitaria, Department of Materials Process Engineering, Nagoya University)
• Motonobu Goto(Department of Materials Process Engineering, Nagoya University)
• Juan García‑Serna(Department of Chemical Engineering and Environmental Technology, High Pressure Processes Group, Universidad de Valladolid)
• Saida Mayela García Montes(Department of Materials Process Engineering, Nagoya University)