Green production of pristine graphene using fluid dynamic force in supercritical CO2.

A green and scalable method was presented for the production of pristine graphene by the exfoliation of graphite using a shear mixer in supercritical CO 2 . The resulting graphene flakes were characterized by transmission electron microscopy, Raman spectroscopy and atomic force microscopy. The synergistic effects of the fluid dynamic force coupled with the supercritical CO 2 actualized the exfoliation of graphite into graphene. The total exfoliation yield reached 63.2%. Up to 79% of the produced graphene was less than five layers, of which monolayer, bilayer and trilayer represented 27%, 25% and 14%, respectively. The average lateral size of the resulting graphene was 5 μm. The Raman spectrum reveals that the graphene was defect free. The prepared graphene was utilized to fabricate flexible, transparent and conductive films on a PET substrate through a vacuum filtration and dry transfer method. The transparency of the film reached 83%, the resistance was 0.83 kΩ/sq, and there was minimal variation, even after the film was bent more than 500 cycles. [ABSTRACT FROM AUTHOR]