Effect of oxygen functional groups on the electrochemical characteristics of reduced graphene oxide for application of supercapacitor thin-film electrode = 산소 관능기 그룹들이 슈퍼커패시터 박막 전극용 환원 그래핀 옥사이드의 전기화학적 특성에 미치는 영향

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For incompletely reduced graphene oxides (RGOs), an effect of oxygen functional groups such as carboxyl, phenol, carbonyl, and quinone on electrochemical capacitive behavior was studied. To prepare RGO thin-film electrodes, a simple fabrication process by (ⅰ) dropping and evaporating the graphene oxide (GO) solution, (ⅱ) irradiating pulsed light, and (ⅲ) heat-treating at 200 ~ 360 °C was applied. It was notable that the pulsed light irradiation was effective to prevent the disfiguring of deposited GO thin-film during the thermal reduction. From XRD analyses, interlayer distances of the RGOs were gradually decreased from 0.379 to 0.354 nm. As increasing the thermal reduction temperature from 200 to 360 °C, XPS O 1s spectra analyses showed that the atomic percentages of carboxyl and phenol of the RGOs were sustained as 5.40 ± 0.36 and 4.77 ± 0.41 at% respectively. Meanwhile, those of carbonyl and quinone of the RGOs were gradually declined from 3.10 to 1.81 and from 1.32 to 0.65 at% with different thermal reduction temperature respectively. For all RGO thin-film electrodes, the specific capacitance from the CV measurement in 6 M KOH was sustained as ca. 220 F/g at the scan of 5 mV/s. However, in 1 M H2SO4, the specific capacitance was gradually decreased from 171 to 136 F/g. After 100,000 cycles in 6 M KOH, 1 M H2SO4, and 0.5 M Na2SO4, the RGO (200 °C) electrodes showed ca. 92, 54, and 104 % of the initial capacitances respectively. The atomic percentages of the oxygen functional groups involved in the pseudocapacitive Faradaic reaction were decreased after the cycle test. Especially in 1 M H2SO4, quinone group was decreased to ca. 48 % of initial atomic percentage, which seems to be a main reason for the drastic reduction of capacitance. The specific pseudocapacitance per unit atomic percentage for either carboxyl or phenol group in 6 M KOH was obtained as 12.59 F/g/at%. For carbonyl group in 1 M H2SO4, it was a slightly deviated value as 13.55 F/g/at%. For qui...
Advisors
Park, Seung-Binresearcher박승빈
Description
한국과학기술원 : 생명화학공학과,
Publisher
한국과학기술원
Issue Date
2014
Identifier
568540/325007  / 020107057
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2014.2, [ ⅶ, 84 p. ]

Keywords

Oxygen functional groups; 슈퍼커패시터; 슈도용량; 박막 전극; 환원 그래핀 옥사이드; 산소 관능기; Reduced graphene oxide; Thin-film electrode; Pseudocapacitance; Supercapacitor

URI
http://hdl.handle.net/10203/196390
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=568540&flag=dissertation
Appears in Collection
CBE-Theses_Ph.D.(박사논문)
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