research article influence of concentration and electrodeposition...

Research ArticleInfluence of Concentration and ElectrodepositionTime on the Electrochemical Supercapacitor Performance ofPoly(34-Ethylenedioxythiophene)Graphene OxideHybrid Material

Nur Hawa Nabilah Azman1 Hong Ngee Lim12 and Yusran Sulaiman12

1Department of Chemistry Faculty of Science Universiti Putra Malaysia (UPM) 43400 Serdang Selangor Malaysia2Functional Device Laboratory Institute of Advanced Technology Universiti Putra Malaysia (UPM) 43400 SerdangSelangor Malaysia

Correspondence should be addressed to Yusran Sulaiman yusranupmedumy

Received 14 August 2016 Revised 27 October 2016 Accepted 8 November 2016

Academic Editor Stefano Bellucci

Copyright copy 2016 Nur Hawa Nabilah Azman et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Poly(34-ethylenedioxythiophene)graphene oxide (PEDOTGO) composites with wrinkled paper-like sheets morphology wereelectropolymerized potentiostatically at 12 V with different electrodeposition times (1ndash30min) and various concentrations of GO(05 10 15 and 20mgmL)The electrochemical properties of PEDOTGO composites as an electrodematerial for supercapacitorwere investigated using cyclic voltammetry electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge(GCD) The CV results revealed that PEDOTGO containing 10mgmL GO and electropolymerized for 10 minutes exhibited thehighest specific capacitance (15717 Fg) This optimum PEDOTGO was found to have energy and power density of 1824Wkgand 49664Whkg respectively at 10 Ag current density The resistance of charge transfer obtained for PEDOTGO is very low(1310Ω) compared to PEDOT (63898Ω) proving that PEDOTGO has a good supercapacitive performance due to the synergisticeffect of the high conductivity of PEDOT and large surface area of GO

1 Introduction

In recent years there has been a greater demand for energystorage devices due to the deficiency of energy sourceThere-fore the development of energy storage device such as super-capacitor is expanding rapidly Supercapacitor also knownas ultracapacitor is an electrical energy storing device whichbridges the gap between batteries and capacitors [1 2] Super-capacitor possesses fast charge-discharge cycle high powerdensity and longer life span and is also environmentallyfriendly compared to battery [3] Supercapacitor has a poten-tial to deliver greater acceleration (through rapid dischargecapability) and enhance the regenerative braking systems(through fast charge capability) for hybrid and pure electricvehicles [4] However the energy density of batteries isgreater in comparison to supercapacitors [5]

Supercapacitors can be classified into twomain categoriesbased on its charge storage mechanism that is electric dou-ble-layer capacitor (EDLC) and pseudocapacitor EDLCstores charge non-Faradaically or electrostatically in doublelayers where there is no electron transfer occurring at theinterface of the electrode [6 7] Graphene activated carbonand carbon nanotubes (CNT) with high porosity and surfacearea are types of carbon-based materials used for EDLC [8]Pseudocapacitor which ismade up of pseudocapacitivemate-rials that is metal oxides and conducting polymers (CPs)stores charges Faradaically or through redox reactions whichoccur at the electrolyteelectrode interface that contribute thecapacitance [9 10]

EDLC compared to pseudocapacitor is able to deliverhigher power density and longer life cycle due to the highporosity mechanical strength and surface area provided by

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2016 Article ID 5935402 10 pageshttpdxdoiorg10115520165935402

2 Journal of Nanomaterials

O O

O O

OH

OH

OHOH

OHOH OH

OH

O O

O

O

O

O

O

O

O

O O

O

O

O

O O

S S

HO

HO

HO

HOOC

COOH

COOH

COOH

COOH

COOminus

COOminus

S+

S+

Figure 1 The interaction between poly(34-ethylenedioxythiophene) (PEDOT) and graphene oxide (GO)

the carbon-based materials [11] Porous electrode materialshelp the penetration of electrolyte and improve the mass-charge transfer between the electrolyte and electrode inter-face thus enhancing the supercapacitive performance [12]Nevertheless EDLC suffers from low energy density Pseu-docapacitor yet can store more energy than EDLC but suffersfrom low cyclic stability and power density [13] Hence bothEDLC and pseudocapacitor materials can be incorporatedtogether to form hybrid composites that can enhance theperformance of supercapacitor through the high surface areaporosity and electrical conductivity provided by the carbon-based materials and CPs In comparison to EDLC and pseu-docapacitor hybrid supercapacitor has better cycling stabilityand relatively large storage capacity [14]

One of the promising CPs for supercapacitor is poly(34-ethylenedioxythiophene) (PEDOT) (Figure 1) which canbe polymerized from 34-ethylenedioxythiophene (EDOT)monomer via electrochemical or chemical method that hashigh conductivity ranging from 10minus2 to 10minus5 Scm [15] How-ever EDOT has poor solubility [16] This major problem canbe overcome by introducing an anionic dopant that is gra-phene oxide (GO) a carbon-based material that can improvethe solubility of EDOTmonomer [17] and simultaneously canincrease the performance of the supercapacitor [18] GO is aderivative of graphene that consists of hydrophilic functionalgroups that is hydroxyl carboxyl and epoxide [3]

In recent times preparations of CPs hybrid with carbon-based materials for supercapacitors have extensively been

conducted in order to fulfill the requirement of the high-per-formance supercapacitor One-step electrodeposition of sul-fonated graphenepolypyrrole (s-GPPy) composite has beensuccessfully prepared and exhibited a specific capacitanceof 310 F gminus1 and ability to retain 71 of its original specificcapacitance after 1500 cycles [19] Shabani Shayeh et al [20]prepared polyanilinereduced graphene oxideAu nanoparti-cles (PANIrGOAuNPs) as a supercapacitor material whichyield a capacitance of 303 F gminus1 and long cycle stabilityPPyGO nanocomposite for supercapacitors has been pre-pared via facile electrochemical codeposition by varying thedeposition time It was found that the longer deposition timeresulted in a lower value of capacitance because of the largerdiffusion resistance of electrolyte ions [21] On the otherhand multilayer graphenePEDOT thin films have been pre-pared by electropolymerization method The multilayer gra-phenePEDOT thin films comprising of six graphene lay-ers showed greatly improved capacitance compared withpure graphenePEDOT thin films and possessed greatercycling stability [22] In addition rGOPPy composite forsupercapacitor was investigated by varying the amount ofGO precursor and it is found that 6mgmL GO precursorexhibits the highest specific capacitanceThe result shows thatconcentration gives significant effect on the composite forsupercapacitor application [8]

Previously we have reported preparation of PEDOTGOhybrid material for supercapacitor via chronoamperometrytechnique at various electropolymerization potentials [23]

Journal of Nanomaterials 3

Our previous result has shown that 12 V is the optimum elec-tropolymerization potential to prepare PEDOTGO hybridmaterial for supercapacitor electrode To the best of ourknowledge a research on the influence of the concentrationof GO and electropolymerization time on the supercapacitorperformance of PEDOTGO has not been reported Thus inthis work PEDOTGO hybrid materials were prepared viapotentiostatic polymerization at 12 V on indium tin oxide(ITO) substrate and the influence of the concentration of GOas a sole dopant and electropolymerization time on the per-formance as supercapacitor material were investigated Thecapacitive performance of PEDOTGO for supercapacitor isfurther investigated using cyclic voltammetry galvanostaticcharge-discharge (GCD) and electrochemical impedancespectroscopy (EIS)

2 Experimental

21 Reagents and Instrumentation Acetone and potassiumpermanganate (KMnO

4) were obtained from SystermMeth-

anol was purchased fromHmbGwhereas potassium chloride(KCl) and 34-ethylenedioxythiophene (EDOT) monomerwere obtained from Sigma-Aldrich respectively Graphiteflake was acquired from Ashbury Inc Phosphoric acid(H3PO4) sulphuric acid (H

2SO4) and hydrogen perox-

ide (H2O2) were attained from Merck All electrochemical

measurements in this work were conducted by means ofthree-electrode system using an Autolab M101 potentiostatequipped with NOVA software The Pt coiled wire was usedas counter electrode whereas AgAgCl was employed asreference electrodesThe working electrode used was indiumtin oxide (ITO) glass (1 cm2) The capacitive performance ofPEDOTGO composites for supercapacitor was investigatedusing cyclic voltammetry where the potential range appliedwas minus05 V to 05 V galvanostatic charge-discharge (GCD)was with various current densities (03 Ag to 20 Ag)and electrochemical impedance spectroscopy (EIS) at open-circuit potential (OCP) was with AC amplitude of 5mV inthe frequency range 01 Hz to 100 kHz The morphology ofthe PEDOTGO composites was studied using field emissionscanning electron microscope (FESEM JEOL JSM-7600F)

22 Preparation of PEDOTGO GO was synthesized viaHummerrsquos method [23] Solutions containing 10mM ofEDOT and different concentrations of GO that is 05 1015 and 20mgmL were prepared in deionized (DI) water(182MΩsdotcm at 25∘C) The EDOT containing GO solutionwas electropolymerized potentiostatically on ITO substrate at12 V [23] with various electropolymerization times rangingfrom 1 to 30min

3 Results and Discussion

31 Morphology The surface morphology of PEDOTGOwith different concentrations of GO and electropolymeriza-tion times was studied using FESEM The FESEM images ofPEDOTGO prepared from different concentrations of GOat 10min are presented in Figure 2 The FESEM images ofPEDOTGO show a significant change with the increment of

the amount of GO in which the wrinkled paper-like sheets ofGO become more prominent and thicker The PEDOTGOwith the maximum content of GO that is 20mgmL GO(Figure 2(d)) shows themost pronounced and thickest wrin-kled paper-like sheets morphology in comparison with otherconcentrations of GO However the morphology of PEDOTwas not observed in all FESEM images due to the presenceof large dopant ion (GO) with the anionic properties thatovershadows PEDOT morphology [16]

In order to investigate the influence of electropolymeriza-tion time on the surface morphology of PEDOTGO FESEMwas performed on PEDOTGO prepared from 10mgmLGO at different electropolymerization times (Figure 3) ThePEDOTGO prepared at various times likewise shows thetypical wrinkled paper-like sheets morphology similarlywhen the GO amount increases The wrinkled paper-likesheetsrsquo morphology of PEDOTGO grows larger and resultedinmore dense and prominentmorphology as the electropoly-merization time prolongs

32 Cyclic Voltammetry

321 Effect of GO Concentration The capacitive propertiesof PEDOTGO prepared from different concentrations ofGO at 10 minutes were studied using cyclic voltamme-try in 10M H

2SO4 The cyclic voltammograms (CVs) of

PEDOTGO with 05 and 10mgmL GO (Figure 4(a)) showbroad quasirectangular shape with wave-like properties asa result of large double-layer capacitance provided by GOthat is a carbon-based material [24 25] whereas CVs ofPEDOTGO with 15 and 20mgmL GO show oblique andnarrow shape demonstrating a large interfacial contact resis-tance with the bulk electrolyte and low ionic propagationbehavior of the PEDOTGO Generally the integrated area ofthe CV of PEDOTGO decreases with the increasing amountof GO However the CV integrated area of PEDOTGOwith 10mgmL amount of GO is higher than PEDOTGOcontaining 05mgmL GO indicating increase in electri-cal double-layer (EDL) capacitance due to the abundanceamount of GO [25] The large surface area of GO providesa more electroactive site for electrochemical reaction [21]

The CV integrated areas of PEDOTGO composites werefurther investigated by calculating the specific capacitance(119862sp) and the ability of a system to store energy using

119862sp =int 119894119889119881]Δ119881119898 (1)

where int 119894119889119881 is the integrated area of the CV ] denotes thescan rate (Vs) Δ119881 is the range of potential applied (V) and119898 is the mass of the electrode material (g) The calculatedvalues of specific capacitance versus concentration of GO areplotted and depicted in Figure 4(b) The specific capacitanceof PEDOTGO with 05mgmL GO is 7534 Fg As the GOconcentration increases to 1mgmL the specific capacitanceobtained is 15717 Fg which is the maximum value of specificcapacitance in this study This could be due to the synergisticeffect of the high conductivity of PEDOT and large surfacearea of GO As the amount of GO increases a larger surface


(a) (b)

(c) (d)Figure 2 FESEM images of PEDOTGO prepared from different concentrations of GO (a) 05mgmL (b) 10mgmL (c) 15mgmL and(d) 20mgmL

(a) (b)

(c)Figure 3 FESEM images of PEDOTGO prepared at different electropolymerization times (a) 1min (b) 10min and (c) 30min


20mgml GO15mgml GO

10mgml GO05mgml GO

minus04 minus02 00 02 04 06 08minus06Potential applied (V) versus AgAgCl

minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(a)

minus20

0

20

40

60

80

100

120

140

160

180

Spec

ific c

apac

itanc

e (F

g)

06 08 10 12 14 16 18 20 2204Concentration of GO (mgml)

(b)

30 min15 min

10 min5 min1 min


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(c)

5 10 15 20 25 300Time (min)

0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)

(d)Figure 4 (a) CVs of PEDOTGO and (b) specific capacitance of PEDOTGO for different concentrations of GO ((i) 05mgmL (ii)10mgmL (iii) 15mgmL and (iv) 20mgmL) (c) CVs of PEDOTGO and (d) specific capacitance of PEDOTGO at different electropoly-merization times ((i) 1min (ii) 5min (iii) 10min (iv) 15min and (v) 30min) Scan rate 01 Vs

area provided by GOwill makemore interaction between theelectrode and electrolyte interface that allows high accessi-bility of electrolyte ions [26] However as the amount of GOincreases to 15 and 20mgmLGO (very high concentration)the specific capacitances decrease to 2445 Fg and 196 FgrespectivelyThismight be due to the nonconductive behaviorof GO [13] that makes the layer become less conductive atthe very high amount of GO and eventually the transfer ofelectrons between the interface of electrolyte and electrode ispartially blocked In addition the electrical conductivity ofPEDOTGO decreases with the high amount of GO due tothe low electrical conductivity of GO which causes the valueof specific capacitance to decrease [27] The results show that

optimum amount of GO is very important to obtain goodcapacitive properties and high specific capacitance value

322 Effect of Electropolymerization Time The capacitiveproperties of PEDOTGO with the maximum specific capac-itance value which is PEDOTGO containing 10mgmL GOwas further studied using cyclic voltammetry at differentelectropolymerization times From Figure 4(c) the CVs ofPEDOTGO electropolymerized at 1 5 and 10min exhibitquasirectangular shape In contrast CVs of PEDOTGOelectropolymerized at 15 and 30min show oblique andnarrow shapes respectively As the electropolymerizationtime is increased from 1 to 5min the CV integrated area


0

50

100

150

200

250Sp

ecifi

c cap

acita

nce (

Fg)

20mgml GO15mgml GO

10mgml GO

05mgml GO

40 60 80 100 120 140 160 180 200 22020Scan rate (mV) vsversus AgAgCl

(a)

0

50

100

150

200

250

Spec

ific c

apac

itanc

e (F

g)

40 60 80 100 120 140 160 180 200 22020Scan rate (mV) versus AgAgCl

30 min

15 min

10 min

5 min

1 min

(b)Figure 5 Specific capacitance of PEDOTGO for (a) different concentrations of GO and (b) different electropolymerization times at differentscan rates (25mVs 50mVs 100mVs 150mVs and 200mVs) in 10M H

2SO4

of PEDOTGO becomes larger When the electropolymer-ization time increases to 10min a maximum CV integratedarea is obtained Nevertheless the CV integrated area shrinkswhen the electropolymerization time is raised to 15minThisphenomenon becomes more pronounced as the electropoly-merization time is further increased to 30min

The specific capacitance values obtained for PEDOTGOwith different electropolymerization time is depicted inFigure 4(d) As the electropolymerization time increasesfrom 1 to 5min the specific capacitance increases whichis from 1987 to 5525 Fg The specific capacitance risestremendously to 15717 Fg as the electropolymerization timeincreases to 10min where the maximum value of specificcapacitance is obtained However the specific capacitancesdecline as the electropolymerization time increases to 15and 30min with specific capacitances of 7944 and 121 Fgrespectively The decreasing values of specific capacitancemay due to the longer electropolymerization time that causesthe polymer chains to grow instead of forming a new chainThus this makes the electrolyte ions difficult to penetratedue to the elongation and thickening of the polymer chainswhich reduce the ability of charge storage of the PEDOTGOcomposite [26] This phenomenon can be clearly seen inthe FESEM images of PEDOTGO in which the wrinkledpaper-like sheet becomes more prominent and dense as theelectropolymerization time increases (Figure 3)

323 Effect of Scan Rate The effect of scan rate on thespecific capacitance of PEDOTGO was performed via cyclicvoltammetry measurements The specific capacitance ofPEDOTGO at different scan rates (25 50 100 150 and200mVs) with different concentrations of GO and differentelectropolymerization times is displayed in Figures 5(a) and5(b) respectively The specific capacitances decrease withthe increasing of scan rate due to the ineffective interactionbetween the electrode materials and electrolyte during the

0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)

H2SO4 Na2SO4KCl KOHElectrolyte (10M)

Figure 6 The specific capacitance of PEDOTGO with 10mgmLGO electropolymerized for 10 minutes in 10M of different elec-trolytes (H

2SO4 KCl Na

2SO4 and KOH) Scan rate 100mVs

fast CV scan [21] During the slow CV scan rate the specificcapacitance increases greatly as a result of the slow iondiffusion from the electrolyte into the electrode materialswhich maximizes the interaction of electrode materials andthe electrolyte [21]

324 Effect of Different Electrolytes on Specific CapacitanceThe capacitive behavior of PEDOTGO was further investi-gated by studying the effect of different electrolytes on thevalue of specific capacitance as the interaction of electrolyteand the electrode materials also plays a crucial part in thesupercapacitor performance Electrolyte provides ionic con-ductivity and assists in the compensation of charge on each ofthe electrodes [28] Figure 6 shows that themaximumspecific


(ii)(i)minus06

minus04

minus02

00

02

04

06

08Po

tent

ial (

V) v

ersu

s Ag

AgC

l

(iii)(iv)

50 100 150 200 250 3000Time (s)

(iv) 20mgml GO(iii) 15mgml GO

(ii) 10mgml GO(i) 05mgml GO

(a)

0

(v) (iv)(ii) (iii)minus06

minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

100 150 200 250 30050Time (s)

(v) 30 min(iv) 15 min

(iii) 10 min(ii) 5 min(i) 1 min

(i)

(b)

(v)(iv)(iii) (ii)

(i) 10 (Ag)(ii) 20 (Ag)(iii) 30 (Ag)

(iv) 40 (Ag)(v) 50 (Ag)

(i)minus06

minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

50 100 150 200 2500Time (s)

(c)

Figure 7 GCD curves of PEDOTGO (a) electropolymerized at 12 V and 10minwith different concentrations of GO (05mgmL 10mgmL15mgmL and 20mgmL) (b) electropolymerized at 12 V containing 10mgmL GO with different electropolymerization times (1min5min 10min 15min and 30min) (c) electropolymerized at 12 V and 10 minutes containing 10mgmL GO with different current densities(10 Ag 20 Ag 30 Ag 40 Ag and 50 Ag)

capacitance is obtained in H2SO4(15717 Fg) followed by

KCl Na2SO4 and KOH with the specific capacitances of

12013 3424 and 186 Fg respectively This is due to thehigh conductivity of H

2SO4(sim08 Scm2 at 25∘C) compared

to other electrolytes [28]

33 Galvanostatic Charge-Discharge (GCD) Figures 7(a) and7(b) demonstrate the GCD profile of PEDOTGO containingdifferent amounts of GO and different electropolymerizationtimes at 10 Ag current density The PEDOTGO containing

10mgmL GO displays the longest discharge time whichextends to 1322 s Figure 7(c) presents the GCD profile ofPEDOTGO with the longest discharge time containing10mgmLGOelectropolymerized for 10min at different cur-rent densitiesThe discharge time of PEDOTGO at high cur-rent density drops which is attributable to the fast charge anddischarge cycle which reduce the accessibility and diffusion ofelectrolyte ions into the electrode active materials [7] All theGCD curves exhibit equilateral triangle shape demonstrat-ing high reversibility during the chargedischarge processes


Table 1 The values of 119877ct ESR and 1205942 and electrical circuit of PEDOT and PEDOTGO containing 10mgmL GO electropolymerized for

10 minutes

119877ct (Ω) ESR (Ω) 1205942 (10minus3) Electrical circuit

PEDOT 63898 8200 012

ESR

CPE

Rct

W

PEDOTGO 1310 3010 1570

ESR CPE

Rct

Cdl

W

[24 29] From the GCD profile of PEDOTGO there is noIR drop occurring for all current densities indicating thatelectrodes have low internal resistance The presence of IRdrop is not good for energy storage devices as there will bea lot of energy loss during the charging-discharging process[21] From the GCD the highest energy and power densityacquired are 1824Wkg and 49664Whkg respectively at acurrent density of 10 Ag for PEDOT electropolymerized in10mgmL GO for 10min

34 Electrochemical Impedance Spectroscopy (EIS) EIS mea-surements were performed to study the resistance of chargetransfer (119877ct) and ion diffusion At the high-frequency regionof theNyquist plot inwhich the119877ct is acquired from the diam-eter of a semicircle describes the charge transfer resistanceoccurs at the interface of electrode and electrolyte [26] FromFigure 8 PEDOT shows large semicircle with the 119877ct valueof 63898Ω (Table 1) Large semicircle demonstrates thatPEDOT has high interfacial resistance with poor behaviorof charge propagation [25] The diameter of the semicirclereduces significantly afterGO is introduced into PEDOTwiththe119877ct value of 1310Ω indicating that PEDOTGOhas bettercharge propagation behavior and low interfacial resistancein comparison to PEDOT The equivalent series resistance(ESR) is obtained at the intercept of the real axis at the high-frequency region of the Nyquist plot which is related to theinternal resistance of the electrode and the total resistanceof solution resistance [26 29] The ESR value of PEDOTGO(3010Ω) is much lower in comparison to PEDOT (82Ω)

The ion diffusion behavior between the electrode andelectrolyte was examined from the slope at the low-frequencyregion of the Nyquist plotTheWarburg slope of PEDOTGOexhibits more vertical line compared to PEDOT indicatingthat PEDOTGO has better capacitive behavior The Nyquistplots of both PEDOT and PEDOTGO were fitted to con-struct equivalent electrical circuits (Table 1) to represent theelectrochemical system of the composites The equivalentelectrical circuits proposed for PEDOT and PEDOTGO

PEDOTPEDOTGO

200 400 600 800 10000

0

200

400

600

800

1000

Z998400 (Ω)

minusZ

998400998400(Ω

)

Figure 8 Nyquist plots of PEDOT and PEDOTGO containing10mgmL of GO electropolymerized for 10min in 10M H

2SO4

Experimental data (dotted line) and fitted data based on equivalentcircuit (solid line)

involve ESR resistance of charge transfer (119877ct) constantphase element (CPE) double-layer capacitance (119862dl) andWarburg (119882)The CPE is used to represent the inhomogene-ity of the electrode surface Low average error (1205942) denotesthat the equivalent electrical circuits are suitable with theelectrochemical system of PEDOT and PEDOTGO

4 Conclusion

PEDOTGO composites for supercapacitor electrode mate-rial have been successfully prepared using potentiostatic elec-tropolymerization The capacitive properties of PEDOTGOare greatly influenced by the electropolymerization time theamount of the GO precursor and the type of electrolyteThe maximum specific capacitance can be obtained with the


optimum and adequate electropolymerization time and con-centration of GO precursor as longer electropolymerizationtime and too much of GO lead to the loss of the specificcapacitance and the performance of the supercapacitor Thehigh amount of GO partially blocks the electron transferbetween electrode material and electrolyte and eventuallyminimizes the electrochemical reaction

Competing Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work is supported by Research Grant Scheme (01-02-13-1388FR) from the Ministry of Education Malaysia

References

[1] JWang Y Xu J Zhu and P Ren ldquoElectrochemical in situ poly-merization of reduced graphene oxidepolypyrrole compositewith high power densityrdquo Journal of Power Sources vol 208 pp138ndash143 2012

[2] H Pan J Li and Y P Feng ldquoCarbon nanotubes for supercapac-itorrdquo Nanoscale Research Letters vol 5 article 654 2010

[3] Q Zhang Y Li Y Feng andW Feng ldquoElectropolymerization ofgraphene oxidepolyaniline composite for high-performancesupercapacitorrdquo Electrochimica Acta vol 90 pp 95ndash100 2013

[4] G A Snook P Kao and A S Best ldquoConducting-polymer-based supercapacitor devices and electrodesrdquo Journal of PowerSources vol 196 no 1 pp 1ndash12 2011

[5] A K Sarker and J-D Hong ldquoElectrochemical reduction ofultrathin graphene oxidepolyaniline films for supercapacitorelectrodes with a high specific capacitancerdquo Colloids and Sur-faces A Physicochemical and Engineering Aspects vol 436 pp967ndash974 2013

[6] B E Conway Electrochemical Supercapacitors Scientific Fun-damentals and Technological Applications Kluwer AcademicPlenum New York NY USA 1999

[7] R Yuksel C Durucan and H E Unalan ldquoTernary nanocom-posite SWNTWO

3PANI thin film electrodes for supercapac-

itorsrdquo Journal of Alloys and Compounds vol 658 pp 183ndash1892016

[8] H-H Chang C-K Chang Y-C Tsai and C-S Liao ldquoElectro-chemically synthesized graphenepolypyrrole composites andtheir use in supercapacitorrdquo Carbon vol 50 no 6 pp 2331ndash2336 2012

[9] B E Conway and W G Pell ldquoDouble-layer and pseudocapaci-tance types of electrochemical capacitors and their applicationsto the development of hybrid devicesrdquo Journal of Solid StateElectrochemistry vol 7 no 9 pp 637ndash644 2003

[10] Z-Y Li M S Akhtar and O-B Yang ldquoSupercapacitors withultrahigh energy density based on mesoporous carbon na-nofibers enhanced double-layer electrochemical propertiesrdquoJournal of Alloys and Compounds vol 653 pp 212ndash218 2015

[11] Z Zhao G F Richardson Q Meng S Zhu H-C Kuan andJ Ma ldquoPEDOT-based composites as electrode materials forsupercapacitorsrdquo Nanotechnology vol 27 no 4 Article ID042001 2015

[12] G Zhu J Yang Y Liu et al ldquoPorous Fe-Mn-O nanocompositessynthesis and supercapacitor electrode applicationrdquo Progress inNatural Science Materials International vol 26 no 3 pp 264ndash270 2016

[13] H-J Choi S-M Jung J-M Seo D W Chang L Dai and J-B Baek ldquoGraphene for energy conversion and storage in fuelcells and supercapacitorsrdquo Nano Energy vol 1 no 4 pp 534ndash551 2012

[14] D Jacob P A Mini A Balakrishnan S V Nair and K RV Subramanian ldquoElectrochemical behaviour of graphene-poly(34-ethylenedioxythiophene) (PEDOT) composite electrodesfor supercapacitor applicationsrdquo Bulletin of Materials Sciencevol 37 no 1 pp 61ndash69 2014

[15] J Hwang F Amy and A Kahn ldquoSpectroscopic study on sput-tered PEDOT A∙PSS role of surface PSS layerrdquo Organic Elec-tronics vol 7 no 5 pp 387ndash396 2006

[16] S Zhang J Hou R Zhang J Xu G Nie and S Pu ldquoElec-trochemical polymerization of 34-ethylenedioxythiophene inaqueous solution containing N-dodecyl-120573-d-maltosiderdquo Euro-pean Polymer Journal vol 42 no 1 pp 149ndash160 2006

[17] K Zhang J Xu X Zhu et al ldquoPoly(34-ethylenedioxythio-phene) nanorods grown on graphene oxide sheets as electro-chemical sensing platform for rutinrdquo Journal of ElectroanalyticalChemistry vol 739 no 1 pp 66ndash72 2015

[18] A Osterholm T Lindfors J Kauppila P Damlin and CKvarnstrom ldquoElectrochemical incorporation of graphene oxideinto conducting polymer filmsrdquo Electrochimica Acta vol 83 pp463ndash470 2012

[19] X Zuo Y Zhang L Si et al ldquoOne-step electrochemical prepa-ration of sulfonated graphenepolypyrrole composite and itsapplication to supercapacitorrdquo Journal of Alloys and Com-pounds vol 688 pp 140ndash148 2016

[20] J Shabani Shayeh A Ehsani M R Ganjali P Norouzi and BJaleh ldquoConductive polymerreduced graphene oxideAu nanoparticles as efficient composite materials in electrochemicalsupercapacitorsrdquo Applied Surface Science vol 353 pp 594ndash5992015

[21] H Zhou G Han Y Xiao Y Chang and H-J Zhai ldquoFacilepreparation of polypyrrolegraphene oxide nanocompositeswith large areal capacitance using electrochemical codepositionfor supercapacitorsrdquo Journal of Power Sources vol 263 pp 259ndash267 2014

[22] S Lee M S Cho H Lee J-D Nam and Y Lee ldquoA facilesynthetic route for well definedmultilayer films of graphene andPEDOT via an electrochemical methodrdquo Journal of MaterialsChemistry vol 22 no 5 pp 1899ndash1903 2012

[23] N H Nabilah Azman H N Lim and Y Sulaiman ldquoEffectof electropolymerization potential on the preparation ofPEDOTgraphene oxide hybrid material for supercapacitorapplicationrdquo Electrochimica Acta vol 188 pp 785ndash792 2016

[24] J Zhang and X S Zhao ldquoConducting polymers directly coatedon reduced graphene oxide sheets as high-performance super-capacitor electrodesrdquo Journal of Physical Chemistry C vol 116no 9 pp 5420ndash5426 2012

[25] P Si S Ding X-W Lou and D-H Kim ldquoAn electrochem-ically formed three-dimensional structure of polypyrrolegra-phene nanoplatelets for high-performance supercapacitorsrdquoRSC Advances vol 1 no 7 pp 1271ndash1278 2011

[26] Y S Lim Y P Tan H N Lim N M Huang and W TTan ldquoPreparation and characterization of polypyrrolegraphenenanocomposite films and their electrochemical performancerdquoJournal of Polymer Research vol 20 no 6 article 156 2013


[27] Y Wu K Zhang J Xu et al ldquoSensitive detection of hydroxy-lamine on Poly (3 4-ethylenedioxythiophene)graphene oxidenanocomposite electroderdquo International Journal of Electrochem-ical Science vol 9 pp 6594ndash6607 2014

[28] C Zhong Y Deng W Hu J Qiao L Zhang and J ZhangldquoA review of electrolyte materials and compositions for elec-trochemical supercapacitorsrdquoChemical Society Reviews vol 44no 21 pp 7484ndash7539 2015

[29] C PanHGu and LDong ldquoSynthesis and electrochemical per-formance of polyaniline MnO

2graphene ternary composites

for electrochemical supercapacitorsrdquo Journal of Power Sourcesvol 303 pp 175ndash181 2016

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


O O

O O

OH

OH

OHOH

OHOH OH

OH

O O

O

O

O

O

O

O

O

O O

O

O

O

O O

S S

HO

HO

HO

HOOC

COOH

COOH

COOH

COOH

COOminus

COOminus

S+

S+

Figure 1 The interaction between poly(34-ethylenedioxythiophene) (PEDOT) and graphene oxide (GO)

the carbon-based materials [11] Porous electrode materialshelp the penetration of electrolyte and improve the mass-charge transfer between the electrolyte and electrode inter-face thus enhancing the supercapacitive performance [12]Nevertheless EDLC suffers from low energy density Pseu-docapacitor yet can store more energy than EDLC but suffersfrom low cyclic stability and power density [13] Hence bothEDLC and pseudocapacitor materials can be incorporatedtogether to form hybrid composites that can enhance theperformance of supercapacitor through the high surface areaporosity and electrical conductivity provided by the carbon-based materials and CPs In comparison to EDLC and pseu-docapacitor hybrid supercapacitor has better cycling stabilityand relatively large storage capacity [14]

One of the promising CPs for supercapacitor is poly(34-ethylenedioxythiophene) (PEDOT) (Figure 1) which canbe polymerized from 34-ethylenedioxythiophene (EDOT)monomer via electrochemical or chemical method that hashigh conductivity ranging from 10minus2 to 10minus5 Scm [15] How-ever EDOT has poor solubility [16] This major problem canbe overcome by introducing an anionic dopant that is gra-phene oxide (GO) a carbon-based material that can improvethe solubility of EDOTmonomer [17] and simultaneously canincrease the performance of the supercapacitor [18] GO is aderivative of graphene that consists of hydrophilic functionalgroups that is hydroxyl carboxyl and epoxide [3]

In recent times preparations of CPs hybrid with carbon-based materials for supercapacitors have extensively been

conducted in order to fulfill the requirement of the high-per-formance supercapacitor One-step electrodeposition of sul-fonated graphenepolypyrrole (s-GPPy) composite has beensuccessfully prepared and exhibited a specific capacitanceof 310 F gminus1 and ability to retain 71 of its original specificcapacitance after 1500 cycles [19] Shabani Shayeh et al [20]prepared polyanilinereduced graphene oxideAu nanoparti-cles (PANIrGOAuNPs) as a supercapacitor material whichyield a capacitance of 303 F gminus1 and long cycle stabilityPPyGO nanocomposite for supercapacitors has been pre-pared via facile electrochemical codeposition by varying thedeposition time It was found that the longer deposition timeresulted in a lower value of capacitance because of the largerdiffusion resistance of electrolyte ions [21] On the otherhand multilayer graphenePEDOT thin films have been pre-pared by electropolymerization method The multilayer gra-phenePEDOT thin films comprising of six graphene lay-ers showed greatly improved capacitance compared withpure graphenePEDOT thin films and possessed greatercycling stability [22] In addition rGOPPy composite forsupercapacitor was investigated by varying the amount ofGO precursor and it is found that 6mgmL GO precursorexhibits the highest specific capacitanceThe result shows thatconcentration gives significant effect on the composite forsupercapacitor application [8]

Previously we have reported preparation of PEDOTGOhybrid material for supercapacitor via chronoamperometrytechnique at various electropolymerization potentials [23]



2 Experimental

















119862sp =int 119894119889119881]Δ119881119898 (1)



(a) (b)


(a) (b)



20mgml GO15mgml GO

10mgml GO05mgml GO


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(a)

minus20

0

20

40

60

80

100

120

140

160

180

Spec

ific c

apac

itanc

e (F

g)


(b)

30 min15 min

10 min5 min1 min


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(c)

5 10 15 20 25 300Time (min)

0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)






0

50

100

150

200

250Sp

ecifi

c cap

acita

nce (

Fg)

20mgml GO15mgml GO

10mgml GO

05mgml GO


(a)

0

50

100

150

200

250

Spec

ific c

apac

itanc

e (F

g)


30 min

15 min

10 min

5 min

1 min


2SO4




0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)



2SO4 KCl Na





(ii)(i)minus06

minus04

minus02

00

02

04

06

08Po

tent

ial (

V) v

ersu

s Ag

AgC

l

(iii)(iv)

50 100 150 200 250 3000Time (s)



(a)

0


minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

100 150 200 250 30050Time (s)



(i)

(b)

(v)(iv)(iii) (ii)

(i) 10 (Ag)(ii) 20 (Ag)(iii) 30 (Ag)

(iv) 40 (Ag)(v) 50 (Ag)

(i)minus06

minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

50 100 150 200 2500Time (s)

(c)











10 minutes


PEDOT 63898 8200 012

ESR

CPE

Rct

W

PEDOTGO 1310 3010 1570

ESR CPE

Rct

Cdl

W




PEDOTPEDOTGO

200 400 600 800 10000

0

200

400

600

800

1000

Z998400 (Ω)

minusZ

998400998400(Ω

)


2SO4



4 Conclusion




Competing Interests


Acknowledgments


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





2 Experimental

















119862sp =int 119894119889119881]Δ119881119898 (1)



(a) (b)


(a) (b)



20mgml GO15mgml GO

10mgml GO05mgml GO


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(a)

minus20

0

20

40

60

80

100

120

140

160

180

Spec

ific c

apac

itanc

e (F

g)


(b)

30 min15 min

10 min5 min1 min


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(c)

5 10 15 20 25 300Time (min)

0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)






0

50

100

150

200

250Sp

ecifi

c cap

acita

nce (

Fg)

20mgml GO15mgml GO

10mgml GO

05mgml GO


(a)

0

50

100

150

200

250

Spec

ific c

apac

itanc

e (F

g)


30 min

15 min

10 min

5 min

1 min


2SO4




0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)



2SO4 KCl Na





(ii)(i)minus06

minus04

minus02

00

02

04

06

08Po

tent

ial (

V) v

ersu

s Ag

AgC

l

(iii)(iv)

50 100 150 200 250 3000Time (s)



(a)

0


minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

100 150 200 250 30050Time (s)



(i)

(b)

(v)(iv)(iii) (ii)

(i) 10 (Ag)(ii) 20 (Ag)(iii) 30 (Ag)

(iv) 40 (Ag)(v) 50 (Ag)

(i)minus06

minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

50 100 150 200 2500Time (s)

(c)











10 minutes


PEDOT 63898 8200 012

ESR

CPE

Rct

W

PEDOTGO 1310 3010 1570

ESR CPE

Rct

Cdl

W




PEDOTPEDOTGO

200 400 600 800 10000

0

200

400

600

800

1000

Z998400 (Ω)

minusZ

998400998400(Ω

)


2SO4



4 Conclusion




Competing Interests


Acknowledgments


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)


(a) (b)



20mgml GO15mgml GO

10mgml GO05mgml GO


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(a)

minus20

0

20

40

60

80

100

120

140

160

180

Spec

ific c

apac

itanc

e (F

g)


(b)

30 min15 min

10 min5 min1 min


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(c)

5 10 15 20 25 300Time (min)

0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)






0

50

100

150

200

250Sp

ecifi

c cap

acita

nce (

Fg)

20mgml GO15mgml GO

10mgml GO

05mgml GO


(a)

0

50

100

150

200

250

Spec

ific c

apac

itanc

e (F

g)


30 min

15 min

10 min

5 min

1 min


2SO4




0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)



2SO4 KCl Na





(ii)(i)minus06

minus04

minus02

00

02

04

06

08Po

tent

ial (

V) v

ersu

s Ag

AgC

l

(iii)(iv)

50 100 150 200 250 3000Time (s)



(a)

0


minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

100 150 200 250 30050Time (s)



(i)

(b)

(v)(iv)(iii) (ii)

(i) 10 (Ag)(ii) 20 (Ag)(iii) 30 (Ag)

(iv) 40 (Ag)(v) 50 (Ag)

(i)minus06

minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

50 100 150 200 2500Time (s)

(c)











10 minutes


PEDOT 63898 8200 012

ESR

CPE

Rct

W

PEDOTGO 1310 3010 1570

ESR CPE

Rct

Cdl

W




PEDOTPEDOTGO

200 400 600 800 10000

0

200

400

600

800

1000

Z998400 (Ω)

minusZ

998400998400(Ω

)


2SO4



4 Conclusion




Competing Interests


Acknowledgments


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




20mgml GO15mgml GO

10mgml GO05mgml GO


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(a)

minus20

0

20

40

60

80

100

120

140

160

180

Spec

ific c

apac

itanc

e (F

g)


(b)

30 min15 min

10 min5 min1 min


minus00015

minus00010

minus00005

00000

00005

00010

00015

Curr

ent (

A)

(c)

5 10 15 20 25 300Time (min)

0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)






0

50

100

150

200

250Sp

ecifi

c cap

acita

nce (

Fg)

20mgml GO15mgml GO

10mgml GO

05mgml GO


(a)

0

50

100

150

200

250

Spec

ific c

apac

itanc

e (F

g)


30 min

15 min

10 min

5 min

1 min


2SO4




0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)



2SO4 KCl Na





(ii)(i)minus06

minus04

minus02

00

02

04

06

08Po

tent

ial (

V) v

ersu

s Ag

AgC

l

(iii)(iv)

50 100 150 200 250 3000Time (s)



(a)

0


minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

100 150 200 250 30050Time (s)



(i)

(b)

(v)(iv)(iii) (ii)

(i) 10 (Ag)(ii) 20 (Ag)(iii) 30 (Ag)

(iv) 40 (Ag)(v) 50 (Ag)

(i)minus06

minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

50 100 150 200 2500Time (s)

(c)











10 minutes


PEDOT 63898 8200 012

ESR

CPE

Rct

W

PEDOTGO 1310 3010 1570

ESR CPE

Rct

Cdl

W




PEDOTPEDOTGO

200 400 600 800 10000

0

200

400

600

800

1000

Z998400 (Ω)

minusZ

998400998400(Ω

)


2SO4



4 Conclusion




Competing Interests


Acknowledgments


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0

50

100

150

200

250Sp

ecifi

c cap

acita

nce (

Fg)

20mgml GO15mgml GO

10mgml GO

05mgml GO


(a)

0

50

100

150

200

250

Spec

ific c

apac

itanc

e (F

g)


30 min

15 min

10 min

5 min

1 min


2SO4




0

20

40

60

80

100

120

140

160

180Sp

ecifi

c cap

acita

nce (

Fg)



2SO4 KCl Na





(ii)(i)minus06

minus04

minus02

00

02

04

06

08Po

tent

ial (

V) v

ersu

s Ag

AgC

l

(iii)(iv)

50 100 150 200 250 3000Time (s)



(a)

0


minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

100 150 200 250 30050Time (s)



(i)

(b)

(v)(iv)(iii) (ii)

(i) 10 (Ag)(ii) 20 (Ag)(iii) 30 (Ag)

(iv) 40 (Ag)(v) 50 (Ag)

(i)minus06

minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

50 100 150 200 2500Time (s)

(c)











10 minutes


PEDOT 63898 8200 012

ESR

CPE

Rct

W

PEDOTGO 1310 3010 1570

ESR CPE

Rct

Cdl

W




PEDOTPEDOTGO

200 400 600 800 10000

0

200

400

600

800

1000

Z998400 (Ω)

minusZ

998400998400(Ω

)


2SO4



4 Conclusion




Competing Interests


Acknowledgments


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(ii)(i)minus06

minus04

minus02

00

02

04

06

08Po

tent

ial (

V) v

ersu

s Ag

AgC

l

(iii)(iv)

50 100 150 200 250 3000Time (s)



(a)

0


minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

100 150 200 250 30050Time (s)



(i)

(b)

(v)(iv)(iii) (ii)

(i) 10 (Ag)(ii) 20 (Ag)(iii) 30 (Ag)

(iv) 40 (Ag)(v) 50 (Ag)

(i)minus06

minus04

minus02

00

02

04

06

08

Pote

ntia

l (V

) ver

sus A

gA

gCl

50 100 150 200 2500Time (s)

(c)











10 minutes


PEDOT 63898 8200 012

ESR

CPE

Rct

W

PEDOTGO 1310 3010 1570

ESR CPE

Rct

Cdl

W




PEDOTPEDOTGO

200 400 600 800 10000

0

200

400

600

800

1000

Z998400 (Ω)

minusZ

998400998400(Ω

)


2SO4



4 Conclusion




Competing Interests


Acknowledgments


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





10 minutes


PEDOT 63898 8200 012

ESR

CPE

Rct

W

PEDOTGO 1310 3010 1570

ESR CPE

Rct

Cdl

W




PEDOTPEDOTGO

200 400 600 800 10000

0

200

400

600

800

1000

Z998400 (Ω)

minusZ

998400998400(Ω

)


2SO4



4 Conclusion




Competing Interests


Acknowledgments


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Competing Interests


Acknowledgments


References










































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials
















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article influence of concentration and electrodeposition...

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