Exfoliation of Graphite into Graphenes for Application to Transparent Electrode and Supercapacitor

Abstract

A high-yielding dispersion of graphene at high concentration in solvent is critical for practical applications. Herein, we demonstrate the formation of stable dispersion of pristine graphene in ethanol by exfoliating graphite flakes into individual graphene layers using a non-ionic polymer surfactant under bath-type sonication. Oligothiophene-terminated poly(ethylene glycol) was synthesized and used as a non-ionic and amphiphilic surfactant for exfoliating graphite into graphenes [1-3]. High-quality graphene film was fabricated from the exfoliated graphene solution by the vacuum filtration method. TEM and SEM reveal that the size of exfoliated graphene flake is larger than 1 ㎛. When the graphene film was treated with nitric acid and thionyl chloride after wahing with tetrahydrofuran, the film showed high performance with a sheet resistance of 0.3 ㏀ sq-1 with a transparency of 74% at 550nm.