Abstract
Graphene has long been envisioned as a promising material in areas, such as energy storage, electromagnetic shielding, and electrochemical sensor. However, the fabrication of graphene is complicated, time-consuming, and hazardous to environment, and thus can hardly realize industrialization. Although the exfoliation of graphite through electrochemical method was believed as an efficient and green approach, the intense current and non-protective action usually lead to the total destruction of the integralgraphitic electrode. In this work, the graphite foil was well-exfoliated into few-layered graphene with proper electrolyte compositions and electrochemical technique. Moreover, the original three-dimensional (3D) integrity of graphite foil can be maintained with the assistance of space-confined exfoliation strategy. The exfoliation process was systematically investigated in terms of electrolyte, applied potential, cation, and anion. The optimized sample exhibited an almost 8.0-folds of increment of double-layer capacitance in comparison with the pristine graphite foil. Eventually, the chemical simulations were employed to elaborate the mechanisms of advanced exfoliation. The space-confined exfoliation reported here is promising for scalable fabrication of 3D graphene materials.
Highlights
Graphene, defined as a plane, hexagonal structure of carbon atoms is regarded as one of the most promising carbonaceous materials with superior properties, including mechanical stiffness, high conductivity, large specific surface area, and decent chemical tolerance (Castro Neto, 2010; Molitor et al, 2011; Avouris and Dimitrakopoulos, 2012)
It is worthy to note that the exfoliated graphite is mostly in the form of powder (Su et al, 2011; Li et al, 2016; Kamali, 2017; Ossonon and Belanger, 2017; Shi et al, 2018), implying the loss of the structural integrity of the graphitic electrode, which is unfavorable for the fabrication of free-standing functional materials
We performed the electrochemical exfoliation in an aqueous electrolyte containing 6.0 ml 0.1 M TBA HSO4 + 12.0 ml 0.2 M KNO3
Summary
Graphene, defined as a plane, hexagonal structure of carbon atoms is regarded as one of the most promising carbonaceous materials with superior properties, including mechanical stiffness, high conductivity, large specific surface area, and decent chemical tolerance (Castro Neto, 2010; Molitor et al, 2011; Avouris and Dimitrakopoulos, 2012). The graphitic materials are employed as the working electrode during the electrochemical exfoliation process. We proposed a space-confined strategy to electrochemically exfoliate graphite foil into a three-dimensional (3D) conductive material. After confining the exfoliation inside the metallic gauze, the original overall 3D architecture of the graphite foil can be well-maintained, which enables the design of free-standing electrodes and stretchable carbonaceous aerogels. This work paves an avenue to fabricate 3D graphene materials with an advanced electrochemical exfoliation method. The exfoliation results were mainly evaluated by the folds of increment of the doublelayer capacitance derived from the integral areas of the cyclic voltammetry (CV) curves
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