title: Facile and Scalable Synthesis Method for High-Quality Few-Layer Graphene through Solution-Based Exfoliation of Graphite.
abstract: Here we describe a facile and scalable method for preparing defect-free graphene sheets exfoliated from graphite using the positively charged polyelectrolyte precursor poly(p-phenylenevinylene) (PPV-pre) as a stabilizer in an aqueous solution. The graphene exfoliated by PPV-pre was apparently stabilized in the solution as a form of graphene/PPV-pre (denoted to GPPV-pre), which remains in a homogeneous dispersion over a year. The thickness values of 300 selected 76% GPPV-pre flakes ranged from 1 to 10 nm, corresponding to between one and a few layers of graphene in the lateral dimensions of 1 to 2 μm. Furthermore, this approach was expected to yield a marked decrease in the density of defects in the electronic conjugation of graphene compared to that of graphene oxide (GO) obtained by Hummers' method. The positively charged GPPV-pre was employed to fabricate a poly(ethylene terephthalate) (PET) electrode layer-by-layer with negatively charged GO, yielding (GPPV-pre/GO)nfilm electrode. The PPV-pre and GO in the (GPPV-pre/GO)nfilms were simultaneously converted using hydroiodic acid vapor to fully conjugated PPV and reduced graphene oxide (RGO), respectively. The electrical conductivity of (GPPV/RGO)23multilayer films was 483 S/cm, about three times greater than that of the (PPV/RGO)23multilayer films (166 S/cm) comprising RGO (prepared by Hummers method). Furthermore, the superior electrical properties of GPPV were made evident, when comparing the capacitive performances of two supercapacitor systems; (polyaniline PANi/RGO)30/(GPPV/RGO)23/PET (volumetric capacitance = 216 F/cm3; energy density = 19 mWh/cm3; maximum power density = 498 W/cm3) and (PANi/RGO)30/(PPV/RGO)23/PET (152 F/cm3; 9 mWh/cm3; 80 W/cm3).
authors.affiliation: Department of Chemistry, Research Institute of Natural Sciences, Incheon National University , 119 Academy-ro, Yeonsu-gu, Incheon, 21022, Republic of Korea.
authors.forename: Boon-Hong
authors.initials: BH
authors.lastname: Wee
authors.affiliation: Department of Chemistry, Research Institute of Natural Sciences, Incheon National University , 119 Academy-ro, Yeonsu-gu, Incheon, 21022, Republic of Korea.
authors.forename: Tong-Fei
authors.initials: TF
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Research Institute of Natural Sciences, Incheon National University , 119 Academy-ro, Yeonsu-gu, Incheon, 21022, Republic of Korea.
authors.forename: Jong-Dal
authors.identifier: http://orcid.org/0000-0003-3767-9355
authors.initials: JD
authors.lastname: Hong
keywords: flexible electrochemical capacitor; graphene oxide; liquid exfoliated graphene; poly(p-phenylenevinylene); supercapacitor