Electrochemically Derived Monolayer Graphene with CVD-Comparable Optoelectrical Properties and High Capacitive...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Scalable synthesis of high-quality monolayer graphene (MG) is crucial for its applications.
• Existing liquid-phase methods often yield oxidized, polydisperse graphene with small flakes.
• Achieving layer-monodisperse MG with desirable properties remains a challenge.

Purpose of the Study:

• To develop a cost-effective, scalable liquid-phase method for synthesizing layer-monodisperse monolayer graphene (MG).
• To characterize the structural, optoelectrical, and energy storage properties of the synthesized MG.
• To demonstrate the superiority of this MG for supercapacitive applications.

Main Methods:

• Engineered electrochemical exfoliation of graphite in 98% H2SO4 electrolyte to form graphite bisulfate (GB).
• Controlled ultrasonic agitation in NMP to exfoliate GB into monolayer graphene.
• Characterization using Raman spectroscopy, microscopy, and electrical/optical measurements.

Main Results:

• Achieved a high MG yield of ~93.3% with large flake sizes (~136 μm2).
• Synthesized MG exhibited low defect density (ID/IG < 0.1) and low oxygen content (2.8%).
• MG demonstrated high transparency (~96.86%), high conductivity (~2.45 ×10^6 S m^-1), and superior supercapacitive performance (~1363 F g^-1).

Conclusions:

• The engineered electrochemical exfoliation method provides a scalable and cost-effective route to high-quality monolayer graphene.
• The synthesized MG possesses excellent optoelectrical properties suitable for transparent conductive films.
• The MG exhibits outstanding potential for high-performance supercapacitive energy storage devices.