posted on 2014-04-23, 00:00authored byKhaled Parvez, Zhong-Shuai Wu, Rongjin Li, Xianjie Liu, Robert Graf, Xinliang Feng, Klaus Müllen
Mass production of
high-quality graphene sheets is essential for
their practical application in electronics, optoelectronics, composite
materials, and energy-storage devices. Here we report a prompt electrochemical
exfoliation of graphene sheets into aqueous solutions of different
inorganic salts ((NH4)2SO4, Na2SO4, K2SO4, etc.). Exfoliation
in these electrolytes leads to graphene with a high yield (>85%,
≤3
layers), large lateral size (up to 44 μm), low oxidation degree
(a C/O ratio of 17.2), and a remarkable hole mobility of 310 cm2 V–1 s–1. Further, highly
conductive graphene films (11 Ω sq–1) are
readily fabricated on an A4-size paper by applying brush painting
of a concentrated graphene ink (10 mg mL–1, in N,N′-dimethylformamide). All-solid-state
flexible supercapacitors manufactured on the basis of such graphene
films deliver a high area capacitance of 11.3 mF cm–2 and an excellent rate capability of 5000 mV s–1. The described electrochemical exfoliation shows great promise for
the industrial-scale synthesis of high-quality graphene for numerous
advanced applications.