Laser reduced graphene for supercapacitor applications

Graphene was prepared by excimer laser irradiation reduction of graphite oxide dissolved in an aqueous solution at different laser energies and irradiation time. The morphologies and structure of the laser reduced graphene were characterized using scanning electron microscopy, low angle X-ray diffraction (XRD) and X-ray photoelectron spectroscopy. The XRD results confirm that the deoxygenation of the graphite oxide sheets occurred almost completely for all laser irradiation conditions used. The graphene fabricated by laser irradiation reduction appears to be randomly aggregated, crumpled, disordered and small sheet solid material. The total amount of oxygen functional groups reduced significantly and the CC/CO intensity ratio increased, however, the atomic percentages of the CO double bond were increased after laser reduction. The laser reduced graphene was used as the electrode active material for supercapacitors and its specific capacitance was evaluated in a two electrode cell in either a 0.5 M Na2SO4 aqueous or a 1 M Tetraethylammoniumtetrafluoroborate acetonitrile based electrolyte. The specific capacitance of the laser fabricated graphene was found to depend on the energy and irradiation time of the laser. The highest specific capacitance was determined to be 141 F/g at 1.04 A/g and 84 F/g at 1.46 A/g in the aqueous and ACN electrolytes, respectively.