Dispersion consisting entirely of trilayer graphene provides film of high specific capacitance

Abstract

The excellent electrical conductivity and tunable bandgap make trilayer graphene (TG) an attractive material for energy storage and electronic applications. The variation in electronic properties of graphene with number of layers present, severely limits the utility of scalable and cost-effective electrochemical exfoliation of graphite for TG synthesis, as the produced graphene is layer-polydispersed. The limitation is further accentuated by the oxygen functionalization, high defect density, and smaller sizes of the produced graphene. Here we produce a dispersion consisting entirely of TG through tailored electrochemical exfoliation of graphite to single-stage III graphite bisulfate (GB) particles, enabling subsequent selective cleaving to TG in the dispersion-favorable solvent DMF. A detailed morphological, structural, and chemical analysis revealed large size of flakes (average size: ∼ 96 μm2) with low defect density (ID∕IG ratio < 0.1) and high C/O ratio (26.78), along with excellent optoelectronic properties (transmittance: ∼ 92.2 % and conductivity: ∼ 2.17 × 106 S m−1) comparable to CVD grown TG. The specific capacitance of TG film is ∼ 259 F g−1 indicating its suitability for energy storage applications.