Exfoliated graphite with relative dielectric constant reaching 360, obtained by exfoliation of acid-intercalated graphite flakes without subsequent removal of the residual acidity
نویسنده
چکیده
Exfoliated graphite (obtained by rapid heating of sulfuric-acid intercalated and subsequently deacidified graphite flakes) is optionally subjected to residual acidity removal, which involves repeated washing with water, such that the pH of the wash water increases from 2 to 7. Compared to washed exfoliated graphite, the unwashed material exhibits lower specific surface area (24 vs. 45 m/g), a higher value (360 vs. 38 at 50 Hz) of the relative dielectric constant (real part), a similar value of the conductivity (50 S/m), a higher value of the specific carbon–contact interfacial capacitance (1.17 vs. 0.04 lF/m), and a lower value of the carbon–contact interfacial resistivity (0.08 vs. 0.27 X cm). The greater concentration of residual intercalate (containing sulfur and oxygen) present without washing contributes to the polarizability without interfering the conduction. The carbon–contact interface is superior when the exfoliated graphite has not been washed. At 2.0 MHz, the relative dielectric constant (real part) remains high (280) and the carbon–contact interfacial specific capacitance remains high (1.13 lF/m). The imaginary part of the relative dielectric constant and the dielectric loss angle are not affected by the washing. The relative dielectric constant of 360 is even higher than the value of 121 for potassium-hydroxide-activated graphite nanoplatelet. 2015 Elsevier Ltd. All rights reserved.
منابع مشابه
A review of exfoliated graphite
Exfoliated graphite (EG) refers to graphite that has a degree of separation of a substantial portion of the carbon layers in the graphite. Graphite nanoplatelet (GNP) is commonly prepared by mechanical agitation of EG. The EG exhibits clinginess, due to its cellular structure, but GNP does not. The clinginess allows the formation of EG compacts and flexible graphite sheet without a binder. The ...
متن کاملThe Electrical Property of Large Few Layer Graphene Flakes Obtained by Microwaves Assisted Exfoliation of Expanded Graphite
Few layer graphene (FLG) was synthesized by -wave assisted exfoliation of expanded graphite in toluene with an overall yield from c.a. 7% to 20%. A significant difference in the absorption of -waves by the expanded graphite and toluene allowed a rapid heating of the medium. The number of FLG sheets varies from 3 to 12, while the lateral size of the sheets exceeds few ms. The obtained FLG exhibi...
متن کاملElectrolytic exfoliation of graphite in water with multifunctional electrolytes: en route towards high quality, oxide-free graphene flakes.
Electrolytic--usually referred to as electrochemical--exfoliation of graphite in water under anodic potential holds enormous promise as a simple, green and high-yield method for the mass production of graphene, but currently suffers from several drawbacks that hinder its widespread adoption, one of the most critical being the oxidation and subsequent structural degradation of the carbon lattice...
متن کاملHigh-yield synthesis of few-layer graphene flakes through electrochemical expansion of graphite in propylene carbonate electrolyte.
High-yield production of few-layer graphene flakes from graphite is important for the scalable synthesis and industrial application of graphene. However, high-yield exfoliation of graphite to form graphene sheets without using any oxidation process or super-strong acid is challenging. Here we demonstrate a solution route inspired by the lithium rechargeable battery for the high-yield (>70%) exf...
متن کاملSynthesis of Graphene Nanoplatelets from Peroxosulfate Graphite Intercalation Compounds
Ultrasonic exfoliation of expanded graphite compound obtained by cold expansion of graphite intercalated with peroxodisulfuric acid was shown to allow the creation of graphene nanoplatelets with thickness of about 5-10 nm. The resulting graphene material contained surface oxide groups. The expanded graphite intercalation compound was exfoliated by ultrasound much easier than thermally expanded ...
متن کامل