Effects of reduction and polystyrene sulfate functionalization on the capacitive behavior of thermally exfoliated graphene

Title
Effects of reduction and polystyrene sulfate functionalization on the capacitive behavior of thermally exfoliated graphene
Authors
Yinan YanTapas Kuila김남훈구본철이중희
Keywords
graphene; thermal exfoliation; capacitance
Issue Date
2013-05
Publisher
Journal of materials chemistry. A, Materials for energy and sustainability
Citation
VOL 1, NO 19, 5892-5901
Abstract
Thermally exfoliated and reduced graphite oxide (TEG) was prepared at high temperature (1000 ℃). The supercapacitor behavior of the resulting TEG would be affected by the specific surface area (SSA) and the surface interactions of the remaining oxygen functional groups with the electrolyte media. The oxygen functional groups on the surface of TEG were controlled by varying the duration of thermal treatment (5, 10, 20, 30 and 45 s). Polystyrene sodium sulfate (PSS) functionalized TEG (PSS-f-TEG) was prepared to aid the interaction with the polar groups of the electrolyte media and its electrochemical performance was measured. Fourier transform infrared and X-ray photoelectron spectroscopy were used for the qualitative and quantitative detection of residual oxygen functionalities in the pristine graphite oxide and resulting TEGs. It was found that the residual oxygen functionalities in the TEGs decreased with increasing thermal treatment time and the SSA increased initially. A maximum SSA of 400.7 ㎡ g-1 was obtained for 30 s thermally treated TEG. The highest specific capacitance value of 278.8 F g-1 was observed for PSS-f-TEG (with 10 s treatment). It was found that the wettability of the TEG was increased after surface modification with PSS as evident from the contact angle analysis. The oxygen functionalities of graphene directly enhanced the specific capacitance by contributing pseudocapacitance. The 1000 charge–discharge cycle test showed long-term electrochemical stability of the electrode materials with 97% retention in specific capacitance.
URI
http://pubs.kist.re.kr/handle/201004/45136
ISSN
20507488
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KIST Publication > Article
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