Reverse-Micelle-Induced Exfoliation of Graphite into Graphene Nanosheets with Assistance of Supercritical CO2

Mass production of graphene with lo -w cost and excellent properties is essential for its practical applications in,energy,. composites, biotechnology, and electronics. Here for the first time we demonstrate that graphite powder can be efficiently exfoliated into monolayered and few-layered rianosheets based on the driving forces,originating from the phase inversion, i.e., from micelles to reverse micelles in the emulsion niicroenvironment}milt by supereritical carbon dioxide (SC CO2). A series of surfactants have been studied, and the experimental results indicate that efficient exfoliation of graphene depends on the suitable surfactant chosen in the SC CO2 solution system. In this work, pblyvinylpyrrolidone (PVP) is confirmed to be an excellent surfactant to play the critical role on exfoliation of graphite, which leads to a high-yield graphene nanosheets (87.7%, <= 3 layers) with concentration of 1.93 mg/mL, large lateral size (up to 5 yin) and low oxidation degree (a C/O ratio of 2028) And the dispersible graphene can be ink-brushed' on A4-size paper to form highly conductive films.(2.41 Omega s q(-1)), which confirms that our exfoliation method remains the integrity of the perfect structure in graphene to the largest extent. Further, the exfoliated graphene was used to prepare electrospun graphene-headed carbon fibers for supertapacitors. The obtained materials deliver a high specific capacitance' of 371.25 F/g, which is 71.6% higher than that of the pristine carbon fibers, and exhibit an excellent rate performance. Thus, this strategy utilizing reverse-micelle-induced Method for exfoliation of graphite to graphene can pave a way for the green solution-ptocessable production of more two-dimensional (2D) nanosheets, which will have great application potential on electronic, biotechnology, energy, and. information storage, etc.