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Powder, Paper and Foam of Few‐Layer Graphene Prepared in High Yield by Electrochemical Intercalation Exfoliation of Expanded Graphite
Author(s) -
Wu Liqiong,
Li Weiwei,
Li Peng,
Liao Shutian,
Qiu Shengqiang,
Chen Mingliang,
Guo Yufen,
Li Qi,
Zhu Chao,
Liu Liwei
Publication year - 2014
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201302730
Subject(s) - graphene , materials science , exfoliation joint , graphite , supercapacitor , intercalation (chemistry) , electrolyte , electrochemistry , chemical engineering , electrode , graphene foam , yield (engineering) , nanotechnology , composite material , aqueous solution , graphene oxide paper , inorganic chemistry , organic chemistry , chemistry , engineering
A facile and high‐yield approach to the preparation of few‐layer graphene (FLG) by electrochemical intercalation exfoliation (EIE) of expanded graphite in sulfuric acid electrolyte is reported. Stage‐1 H 2 SO 4 ‐graphite intercalation compound is used as a key intermediate in EIE to realize the efficient exfoliation. The yield of the FLG sheets (<7 layers) with large lateral sizes (tens of microns) is more than 75% relative to the total amount of starting expanded graphite. A low degree of oxygen functionalization existing in the prepared FLG flakes enables them to disperse effectively, which contributes to the film‐forming characteristics of the FLG flakes. These electrochemically exfoliated FLG flakes are integrated into several kinds of macroscopic graphene structures. Flexible and freestanding graphene papers made of the FLG flakes retain excellent conductivity (≈24 500 S m −1 ). Three‐dimensional (3D) graphene foams with light weight are fabricated from the FLG flakes by the use of Ni foams as self‐sacrifice templates. Furthermore, 3D graphene/Ni foams without any binders, which are used as supercapacitor electrodes in aqueous electrolyte, provide the specific capacitance of 113.2 F g −1 at a current density of 0.5 A g −1 , retaining 90% capacitance after 1000 cycles.