Cathodic exfoliation of graphite into graphene nanoplatelets in aqueous solution of alkali metal salts
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Cathodic exfoliation of graphite into graphene nanoplatelets in aqueous solution of alkali metal salts Md Habibullah Dalal1, Chong-Yong Lee1,*, and Gordon G. Wallace1,* 1
ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM, Innovation Campus, University of Wollongong, Wollongong, NSW 2500, Australia
Received: 9 July 2020
ABSTRACT
Accepted: 16 October 2020
Electrochemical exfoliation has emerged as a green, effective and scalable route for mass production of graphene. Cathodic exfoliation of graphite, offers a direct production of high quality and low defect graphene. However, the protocols for cathodic exfoliation reported to date, use mostly non-aqueous electrolytes which require extended period of intercalation, and post-treatment to further exfoliate the intercalated graphene layers. In contrast, the employment of environment friendly aqueous-based electrolytes, coupling with a shorter exfoliation period would be attractive features of any new protocol. Here, we demonstrate efficient cathodic electrochemical exfoliation of graphite to graphene nanoplatelets in aqueous electrolytes using common and inexpensive alkali-metal salts such as KCl. The key driving force to exfoliate graphite successfully in aqueous electrolyte is applying a sufficiently high voltage, and a high salt concentration which facilitate cation intercalation, and promotes hydrogen evolution to exfoliate the graphene. The cathodic exfoliated graphene nanoplatelets using KCl aqueous electrolyte exhibits a low defect density (ID/IG of 0.06, a C/O ratio of 57.8), high graphite exfoliation yields ([ 80%) in short times (\ 10 min for a graphite foil of 1 cm 9 1 cm 9 0.0254 cm, 30.0 mg). The highly conductive structure consists mainly of 10–13 layers graphene sheets that serve as an excellent support material for electrocatalytic reactions. This environment-benign aqueous-based cathodic electrochemical exfoliation of graphite opens a new opportunity in large-scale and low-cost production of high-quality graphene nanoplatelets.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Handling Editor: Gregory Rutledge.
Address correspondence to E-mail: [email protected]; [email protected]
https://doi.org/10.1007/s10853-020-05468-8
J Mater Sci
Introduction Graphene, a two dimensional carbon material with extraordinary electronic, thermal, mechanical and optical properties has seen opportunities for widespread application [1–4]. However, limited scalable, cost effective and ecofriendly simple reproducible processing methods that deliver high quality materials limit widespread translation. Several approaches for the production of graphene have been developed such as mechanical exfoliation [1, 4], chemical vapour deposition (CVD) [5], arc-discharge method [6], shear exfoliation in liquids [7], microwave assisted production, [8, 9] reduction of graphene oxide (GO) [10] and liquid phase exfoliation [11]. Among them, CVD grown graphene can yield high quality graphene, however the major
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