Preparation of Graphene Sheets by Electrochemical Exfoliation of Graphite in Confined Space and Their Application in Transparent Conductive Films

Abstract

A novel electrochemical exfoliation mode was established to prepare graphene sheets efficiently with potential applications in transparent conductive films. The graphite electrode was coated with paraffin to keep the electrochemical exfoliation in confined space in the presence of concentrated sodium hydroxide as the electrolyte, yielding ∼100% low-defect (the D band to G band intensity ratio, I/I = 0.26) graphene sheets. Furthermore, ozone was first detected with ozone test strips, and the effect of ozone on the exfoliation of graphite foil and the microstructure of the as-prepared graphene sheets was investigated. Findings indicate that upon applying a low voltage (3 V) on the graphite foil partially coated with paraffin wax that the coating can prevent the insufficiently intercalated graphite sheets from prematurely peeling off from the graphite electrode thereby affording few-layer (<5 layers) holey graphene sheets in a yield of as much as 60%. Besides, the ozone generated during the electrochemical exfoliation process plays a crucial role in the exfoliation of graphite, and the amount of defect in the as-prepared graphene sheets is dependent on electrolytic potential and electrode distance. Moreover, the graphene-based transparent conductive films prepared by simple modified vacuum filtration exhibit an excellent transparency and a low sheet resistance after being treated with NHNO and annealing (∼1.21 kΩ/□ at ∼72.4% transmittance).

Electrochemically Exfoliated Graphite/Cu/Cu2O Composites and Their Photocatalytic Activity

“…This phenomenon is allegedly caused by the ability of Cu 2+ to work as a reducing agent in the reduction of oxygenated carbonaceous compounds under microwave irradiation. A similar result has been reported by Li et al in the process of graphene oxide reduction by metallic Cu [31]. Figure 2 (a) shows the x-ray diffractograms of raw graphite, EG, EG/Cu/Cu2O A, and EG/Cu/Cu2O B.…”

High-yield scalable graphene nanosheet production from compressed graphite using electrochemical exfoliation

“…Wang et al . demonstrated that paraffin coating outside the graphite electrode could effectively confine the electrochemical exfoliation to a defined volume 38 . However, intensive sonication in N-Methyl-2-pyrrolidone and further centrifugation were used as post-processing in this case.…”

A flexible solid-state supercapacitor based on graphene/polyaniline paper electrodes

“…Additional multi-steps are needed to reduce such functional graphene for supercapacitor applications. Electrochemical exfoliation, as a green method for preparing graphene sheets, owns unique advantages including easy operation, low cost, scalable production and controllable reaction conditions [12][13][14][15] . These traits enable electrochemical exfoliation a promising method to prepare high-quality and cost-effective graphene sheets for various applications.…”