Supercritical CO2 processing to improve the electrochemical properties of graphene oxide

Porous graphene oxide (GO) structures at different oxidation levels have been obtained by a SC-CO2 assisted process performed at 200 bar, 35 °C and different durations up to 24 h. Supercritical CO2 processing was aimed at exfoliating and reducing graphene oxide. Different techniques were used to characterize the materials obtained: transmission electron microscopy (TEM), Raman and FT-IR Spectroscopy, X-ray diffraction analysis and N2 adsorption-desorption at 77 K. The materials with high surface area up to 930 m2/g, obtained after SC-CO2 treatment, exhibited unique mesoporous structure based on curve graphene sheets and a high capacitive performance with values of 253 F/g at 1 A/g and of 210 F/g at 16 A/g; moreover, a good long cycle stability in aqueous electrolytes (higher than 90% after 2 × 103 cycles) has been also obtained. SC-CO2 processing proved to be successful and simple to be realized, producing high performance materials, characterized by high specific surface areas and supercapacitive performances.