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羧基功能化和表面活性劑修飾對石墨烯電化學性能的影響

福彩开奖2019045 www.jywae.icu 第31卷 第2期 無 機 材 料 學 報

V ol. 31

No. 2

2016年2月

Journal of Inorganic Materials Feb., 2016

Received date: 2015-08-13; Modified date: 2015-10-19; Published online: 2015-11-20

Foundation item: Qingdao Municipal Science and Technology Program (13-1-4-219-jch); Open Fund of Key Laboratory of Inorganic Coating

Materials, Chinese Academy of Sciences (KLICM-2012-06); National Natural Science Foundation of China (51172113 & 51373086); International Science & Technology Cooperation Program of China (2014DFA60150)

Biography: YU Jian-Hua (1984–), female, assistant professor. E-mail: [email protected]//www.jywae.icu/doc/c54cb516571252d380eb6294dd88d0d232d43c70.html Corresponding author: DONG Li-Feng, professor. E-mail: [email protected]//www.jywae.icu/doc/c54cb516571252d380eb6294dd88d0d232d43c70.html

Article ID: 1000-324X(2016)02-0220-05 DOI: 10.15541/jim20150378

Superior Electrochemical Performance of Graphene via Carboxyl

Functionalization and Surfactant Intercalation

YU Jian-Hua 1,2, XU Li-Li 1, ZHU Qian-Qian 1, WANG Xiao-Xia 1, YUN Mao-Jin 3, DONG Li-Feng 1

(1. College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China; 2. Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899, China; 3. College of Physics Science, Qingdao University, Qingdao 266071, China)

Abstract: Superior capacitance of carboxyl functionalized and surfactant-intercalated graphene were prepared by a relatively simple with two-step solution-based processing technique. In comparison to pristine graphene, surface car-boxyl functionalization and surfactant intercalation can tailor its specific capacitance from 50 F/g to 230 F/g. Mean-while, the modified materials retain more than 95% of their capacitance after 800 charge-discharge cycles, demon-strating good cyclic stability. Surfactant itself cannot improve the performance of pristine graphene as graphene inter-calated with surfactant has a specific capacitance of 45 F/g, however, carboxyl groups can dramatically enhance spe-cific capacitance to 130 F/g. The excellent performance of functionalized graphene emphasizes the importance of con-trolling its surface chemistry.

Key words: graphene; functionalization; electrochemical performance

Supercapacitors, which are also called electrochemical capacitors (ECs) or ultracapacitors, have attracted much attention in recent years because of their pulse power sup-ply, long cyclic life (>100,000 cycles), simple operational mechanism, and high dynamics of charge propagation [1]. Furthermore, in comparison with batteries, ECs usually have much higher rate capabilities suitable for special re-quirements in electronics, AC-line filtering, aircraft, en-ergy storage devices, uninterrupted or emergency power supplies, and electric vehicles [2]. A unit cell of an electrical double-layer capacitor (EDLC) displays the characteristics of a double-layer capacitor at the electrode/electrolyte interface, where electric charges are accumulated on the electrode surfaces and ions of opposite charge are ar-ranged in the electrolyte side [3]. In order to improve the performance of supercapacitors, most research is fo-cused on using innovative electrode materials, appro-priate electrolytes, and tuning electrode/electrolyte in-terface properties.

Graphene, the two-dimensional (2D) unit of three-di-mensional (3D) bulk material graphite, has received sig-nificant attention due to its extraordinary properties [4-5]. It has captured the imagination of engineers for a variety of

electronics, optical, sensing, microfluidics, manufacturing, and clean energy device applications [6-7]. In this study, a Wurtz-type reductive coupling (WRC) reaction was util-ized as a bottom-up method for rapid preparation of high-quality pristine graphene, and the samples obtained were labeled as PG [8]. However, the availability of as-prepared graphene is confined to high cohesive van der Waals energy (5.9 kJ/mol carbon)[9] adhering graphitic sheets to one another. Thus, pristine graphene-based mate-rials actually exhibit unsatisfactory capacitance because of inevitable aggregation of graphene sheets. The oxidation chemistry of graphene is similar to that used to function-alize single-walled carbon nanotubes (SWCNTs)[10], which yields a variety of oxygen functionalities (–OH, –O–, and –COOH), primarily at “defect” sites on SWCNT ends. These surface functionalities of graphene can inhibit gra-phene sheets from aggregation and thereby, improve their electrochemical properties. Pristine graphene has tiny amount of oxygen functionalities on their surface. Surfac-tant intercalation can inhibit graphene sheet aggregation, enhance surface wettability, and thus improve their spe-cific capacitance. Lomeda, et al [11] employed aryl dia-zonium salts to enhance the solubility of graphene

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