Esfoliação do grafite em fluido supercrítico CO2 assistido com surfactante de origem natural

Abstract

Graphene is a material with excellent electrical, electronic, mechanical and optical properties, and has a wide range of applications in different sectors, ranging from the manufacture of energy storage devices to the biomedical sector. Although there are different methodologies proposed by authors for their production, an efficient procurement route, which combines high yield, quality (defect-free structure), sustainability and production on a viable industrial scale, is still a challenge. In this perspective, the present work is related to obtaining graphene from the exfoliation of graphite in a supercritical medium, using carbon dioxide (CO2) assisted with natural surfactant, cardanol. In this study, experimental parameters are evaluated, such as system pressure, the presence of ethanol in the graphite during exfoliation, the potential of cardanol as a surfactant in excretion in a supercritical medium. The materials were characterized by Scanning Electron Microscopy with Field Emission (SEM-FEG), Transmission Microscopy (TEM), Atomic Force Microscopy (AFM), X-Ray Diffraction (DRX), and RAMAN Spectroscopy (FT- Raman). Exfoliation was efficient using the dispersion of graphite in a solution of cardanol and ethanol in supercritical carbon dioxide, at a temperature of 40ºC, in a pressure ramp between 150 and 250bar. In these conditions, stack of sheets 15-50nm thick were obtained.