research article fabrication of pani/c-tio composite ...pani and moox, which exhibits high speci c...

Research ArticleFabrication of PANIC-TiO

2Composite Nanotube Arrays

Electrode for Supercapacitor

Chengcheng Zhang1 Changjian Peng1 Biao Gao1 Xiang Peng2 Xuming Zhang2

Jingyuan Tao1 Jinhan Kong1 and Jijiang Fu1

1The State Key Laboratory of Refractories and Metallurgy School of Materials and MetallurgyWuhan University of Science and Technology Wuhan 430081 China2Department of Physics and Materials Science City University of Hong Kong Kowloon Hong Kong

Correspondence should be addressed to Biao Gao gaobiaowusteducn and Jijiang Fu fujijiangwusteducn

Received 18 January 2015 Accepted 17 May 2015

Academic Editor Ovidiu Ersen

Copyright copy 2015 Chengcheng Zhang et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Polyanilinecarbon doped TiO2composite nanotube arrays (PANIC-TiO

2NTAs) have been prepared successfully by electrode-

positing PANI in C-TiO2NTAs which were prepared by directly annealing the as-anodized TiO

2NTAs under Ar atmosphere The

organic residual in the TiO2NTAs during the process of anodization acts as carbon source and is carbonized in Ar atmosphere

to manufacture the C-TiO2NTAs The specific capacitance of the PANIC-TiO

2electrode is 1208mF cmminus2 at a current density of

01mA cmminus2 and remains 1043mF cmminus2 at a current density of 2mA cmminus2 with the calculated rate performance of 863 After5000 times of charge-discharge cycling at a current density of 02mA cmminus2 the specific capacitance retains 887 compared to thefirst cycle All these outstanding performances of the as-prepared PANIC-TiO

2NTAs indicate it will be a promising electrode for

supercapacitor

1 Introduction

Energy shortage crisis and environmental pollution are globalproblems which promote the scientific research to developclean energy and corresponding energy storage system [12] Electrochemical capacitor also called ultracapacitor isconsidered as one of the most promising energy storagedevices which is widely used to satisfy the energy demandinmobile equipments hybrid electric vehicles and aerospacefields because of its high power density energy densityand excellent cycle performance [3ndash5] Recently the faradicpseudocapacitors-type supercapacitors (SCs) have attractedmuch attention derived from the exhibited higher specificcapacitance stemming from the reversible redox reactionscompared with the electric double-layer capacitors Variouspseudocapacitive materials such as conducting polymersand transition-metal oxideshydroxides have been studiedextensively Among them polyaniline (PANI) is a promisingcapacitive material because of its large theoretical faradicpseudocapacitance (as high as 1145 F gminus1) high conductivity

low cost facile synthesis and fast dopingdedoping rate [6ndash9] However the relatively poor cycle stability of PANI due tothe swelling and consequent breakage of the structures duringthe charge-discharge process hinders its wide application[10] Thus maintaining the structure stability in cycling iscrucial for high performance PANI-based supercapacitor [11]PANI supported by other mechanically stable materials suchas carbon nanotube carbon nanofiber [12] graphene [13]Si [14] exhibited improved cycle stability However mostof these supporting materials are of powder which needfurther mixing with conductive agent and binder before thesupercapacitor assembling process which will decrease thespecific capacitance in some sense

TiO2nanotube arrays (NTAs) fabricated directly and

adhered strongly to the underlying Ti substrate by simpleanodization is a promising supporting material for PANIloading which provides large active surface areas and robustscaffold Its hydrophilic surface and controllable dimension(including diameter and tube spacing) in favor of the uniformdeposition and efficient utilization of conducting polymer

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2015 Article ID 140596 7 pageshttpdxdoiorg1011552015140596

2 Journal of Nanomaterials

[15 16] However TiO2with poor conductivity hinders

electrodepositing PANI and goes against the rate ability ofsupercapacitor In very recently we improved the conduc-tivity of TiO

2by directly nitriding TiO

2NTAs to form well

conductive TiNNTAs acting as support materials for loadingPANI and MoOx which exhibits high specific capacitanceand excellent cycle stability [17 18]

In this work we demonstrated another conductive sup-port material carbon doped TiO

2nanotube arrays (C-TiO

2

NTAs) to maintain the PANI structure PANI can be easilydeposited on the surface to form uniform PANI and C-TiO

2

nanotube arrays (PANIC-TiO2NTAs) by the electrochem-

ical deposition Because of directional channel for electronstransport and the suitable tube space for the electrolytepermeating the PANIC-TiO

2NTAs electrode exhibits high

specific capacitance of 1208mF cmminus2 at the current densityof 01mA cmminus2 and it also remains 863 when the cur-rent density increases to 2mA cmminus2 It expresses wonderfulcycling performance with the specific capacitance retentionof 887 even after 5000 cycles The results demonstratethat the synthesized PANIC-TiO

2NTAs nanocomposite has

great potential applications for SCs

2 Experimental Details

All chemicals used are of analytical grade Electrochemicalanodization was adopted for TiO

2preparation with a typical

two-electrode configuration of electrochemical anodizationwhere a piece of Ti foil (1sdot1sdot05 cm3) was used as anodeand a piece of graphite plate was served as cathode with1 cm separation powered by a direct current power sup-ply (IT6834 ITECH China) The electrolyte was NH

4F

(05 wt) CH3OH (5 vol) and deionized water (5 vol)

in ethylene glycol The applied potential was 60V and lastedfor 30min

To produce the C-TiO2NTAs we developed an easy

annealing processing by utilizing the residual organic agencyafter anodization in ethylene glycol based electrolyte Indetail the as-anodized TiO

2NTAs was directly calcined in

a tube furnace at 500∘C for 3 h in Ar atmosphere with theheating rate of 15∘Cmin [19 20]

Controlled electropolymerization was used in a three-electrode system with a Pt foil (2sdot2 cm2) as the counterelectrode saturated calomel electrode (SCE) as the referenceelectrode TiO

2NTAs and C-TiO

2NTAs as the working

electrode to fabricate the composite NTAs In general theC-TiO

2NTAs was used as working electrode which was

subjected to repeating potential scanning in 05M H2SO4

solution containing 005M aniline in the range from minus06to 10 V at the scan rate of 50mVs for 15 and 30 cyclesrespectively

The samples were characterized by SEM (FE-SEM FEINova 400Nano) X-ray diffraction (XRD Philips X1015840 Pert Pro)with Cu K120572 radiation of wavelength of 15416 A in the rangeof 20ndash80∘ (2120579) FTIR Spectrometer (Perkin Elmer 1600)and X-ray photoelectron spectroscopy (ESCALB MK-II VGInstruments UK)

Electrochemical measurements were carried out using aCHI 660C instrument The three-electrode cell consisted ofa SCE as the reference electrode a 2sdot2 cm2 platinum plate asthe counter electrode and PANIC-TiO

2sample (1sdot1 cm2) as

the working electrode 1MH2SO4solution served as the elec-

trolyte at room temperature The cyclic voltammetry (CV)was performed between 0 and 1V (versus SCE) at differentscanning rate Galvanostatic charge-discharge curves weremeasured at different current density over the voltage rangeof 0ndash06V (versus SCE) Cycling stability performance wasconducted with a charge-discharge tester (Land CT2001AWuhan LAND Electronics Co Ltd China)

3 Results and Discussion

Figures 1(a) and 1(b) show the SEM images of TiO2NTAs and

C-TiO2NTAs obtained from annealing as-anodized TiO

2

NTAs under air and Ar respectively It is obvious that themorphologies of TiO

2NTAs and C-TiO

2NTAs are of no

significant difference The as-obtained highly ordered andwell-separated C-TiO

2NTAs have a length of about 9 120583m

interior diameter of about 110 nm and tube wall thicknessof about 20ndash25 nm As the XRD pattern of TiO

2NTAs and

C-TiO2NTAs shown in Figure 1(c) the diffraction peaks can

be attributed to anatase TiO2and titanium substrate and no

distinguished difference is observed between the TiO2NTAs

(1) and C-TiO2NTAs (2) Figure 1(d) displays the XPS full

spectra for TiO2NTAs (1) and C-TiO

2NTAs (2) C Ti and

O peaks are observed for C-TiO2NTAs while only Ti and O

peaks are observed for TiO2NTAsThe top right corner inset

shows the high-resolution C 1s spectra The peak at 2819 andweak peak at 2846 eV are attributed to Ti-C and C-C [21]The XPS results indicate that carbon was doped into the TiO

2

NTAs through the residual ethylene glycol reacting with theas-anodized amorphous TiO

2during annealing in Ar While

during heating in air the residual ethylene glycol can reactwith O

2forming CO

2and H

2O resulting in formatting pure

TiO2NTAs Figures 1(e) and 1(f) show the electrochemical

impedance spectroscopy of TiO2NTAs and C-TiO

2NTAs

respectively to identify their conductivity Compared to theresistance of the TiO

2NTAs (20 kΩ) the resistance of C-TiO

2

NTAs decreased by 3 orders of magnitude to 18Ω It indicatesthat the C-TiO

2NTAs has an excellent conductivity which

will be of benefit for aniline monomer electropolymerizingon tube wall

Figures 2(a) and 2(b) show the SEM images of thePANI deposited on TiO

2NTAs and C-TiO

2NTAs by elec-

tropolymerization in 005M aniline sulfuric acid solutionfor 15 cycles named PANITiO

2-15 and PANIC-TiO

2-15

respectively The typical PANIC-TiO2-15 nanotube has a

smaller interior diameter of 80 nm and its tube wall is 35ndash40 nm which is thicker than that of the C-TiO

2NTAs due

to the PANI depositing However for the PANITiO2-15

the diameter and tube wall are the same as the origin TiO2

nanotube The inset is corresponding electrochemical CVcurves of the PANI deposition process of them As for C-TiO2NTAs obvious redox peaks were observed and the peak

current increases with the cycle number increasing which

Journal of Nanomaterials 3

500nm

2120583m

(a)

500nm

2120583m

(b)

20 30 40 50 60 70 80

(2)

(1)

Inte

nsity

(au

)

2120579 (deg)

TiO2

Ti

(c)

1400 1200 1000 800 600 400 200 0Binding energy (eV)

C-TiC-C

286 284 282 280

t = 10min

(1)

C1s

Ti L

MM

1Ti

LM

MO

KLL Ti

2sO

1s

Ti3s Ti3p

(2)

Ti2

P 32

Ti2

P 12

minus400minus200

Inte

nsity

(au

)

(d)

0 8000 16000 24000 32000

0

4000

8000

12000

16000

Z998400 (ohm)

minusZ998400998400

(ohm

)

TiO2

(e)

0 20 40 60 80

0

20

40

60

80

100

120

140

Z998400 (ohm)

minusZ998400998400

(ohm

)

C-TiO2

(f)

Figure 1 SEM images of top- and cross-section (inset) of TiO2NTAs (a) and C-TiO

2NTAs (b) XRD patterns (c) and XPS full spectra (d) of

TiO2NTAs (1) and C-TiO

2NTAs for (2) the inset of (d) is the fine spectra of C 1s EIS plots of TiO

2NTAs (e) and C-TiO

2NTAs (f) in 1M

H2SO4solution


500nm

minus0003minus0002minus0001000000010002000300040005

00 04 08 12Potential (V versus SCE)

minus08 minus04

Curr

ent (

A)

(a)

500nm

00 04 08 12minus005minus004minus003minus002minus001000001002003004

Potential (V versus SCE)

Curr

ent (

A)

minus08 minus04

(b)

500nm

(c)

Figure 2 SEM for TiO2(a) and C-TiO

2(b) deposited in 005M aniline sulfuric acid solution for 15 cycles inset picture is their corresponding

CV plots of polymerization process (c) is PANIC-TiO2for 30 cycles

indicates that polymerization reaction has occurred How-ever redox peak was not appeared at the CV curves collectedfor TiO

2NTAsduringwhole depositionThese results suggest

that C-TiO2NTAs are easier for electrochemical deposition

for PANI due to the enhanced conductivity compared toTiO2NTAs The SEM image of PANIC-TiO

2-30 is shown in

Figure 2(c) indicating that the C-TiO2nanotubes are packed

by the deposited PANI after polymerizing for 30 cycles Itwould block the electrolyte from contacting the inner PANIresulting in the fact that it will not be possible to make fulluse of the as-polymerized PANI On the other hand theaccumulated PANI because of lacking firmly support may beeasy to topple downwhich is antagonistic to the cycle stabilityand rate capability

The FTIR spectrum of the C-TiO2NTAs before and after

depositing PANI is shown in Figure 3 For C-TiO2in curve

(1) the peak at 1350 cmminus1 is attributed to the formation ofcarbonate or carboxylate species and the peak at 1600 cmminus1corresponding to the stretching vibration modes of water

or hydroxyl groups absorbed on C-TiO2[22] Besides the

two peaks at 1349 cmminus1 and 1599 cmminus1 are attributed to theformation of carbonate or carboxylate species and hydroxylgroups respectively other peaks are found for PANIC-TiO

2

(curve (2)) The peaks at 1561 and 1483 cmminus1 belonged tothe C=C stretching of the quinoid ring and benzenoid ringrespectively Those at 1263 and 1168 cmminus1 are attributed toC-N stretching of the secondary aromatic amine The peakat 813 cmminus1 is ascribed to the out-of-plane bending of C-H on the 14-disubstituted ring The peak at 1220 cmminus1 canbe attributed to various stretching and bending vibrationsassociated with the C-C bond [23] The peak at 1168 cmminus1is referred to as the ldquoelectronic-like bandrdquo and its intensityis considered as a measure of the degree of delocalization ofelectrons onpolyaniline [24] From the FTIR spectra it can befurther concluded that PANI was deposited onto the C-TiO

2

NTAs nanocomposite electrode after the electrochemicaldeposition process


2500 2000 1500 1000 500

1263

1561

1350

(2)

(1)

813

1168

1220

1349

1483

1599

1600

Wavenumber (cmminus1)

Tran

smitt

ance

()

Figure 3 FTIR spectrum of C-TiO2and PANIC-TiO

2

00 02 04 06 08 10

0

10

20

30

00 02 04 06 08 10minus10

minus05

000510

(2) D

CBA

(1)

A998400B998400 C998400 D998400

minus10


Curr

ent (

mA

cmminus2)

(1)(2) PANIC-TiO2-15

2C-TiO

2C-TiOPotential (V versus SCE)

Curr

ent (

mA

cmminus2)

Figure 4 CV curves of C-TiO2and PANIC-TiO

2-15 at a scan rate

of 50mV sminus1

CV tests were performed to study the electrochemicalproperties of the PANIC-TiO

2NTAs electrode in 1MH

2SO4

solution As shown in Figure 4 CV curve of PANIC-TiO2-

15 NTAs displays a larger area compared with that of theoriginal C-TiO

2NTAs at the scan rate of 50mV sminus1 It exhibits

four pairs of redox peaks of PANI which implies a highpseudocapacitance The first pair of redox peaks AA1015840 (at023015 V) can be ascribed to the transformation betweenemeraldine and pernigraniline states [15] the peaks BB1015840 (at034025V) and CC1015840 (at 050041 V) derived mainly fromthe redox reactions of dimers oligomers and the degra-dation products including p-benzoquinone quinoneiminep-aminodiphenylamine hydroquinone and p-aminophenol[23 25] and the peaks DD1015840 (at 058056V) can be ascribedto the transformation between emeraldine andpernigranilinestates [17]

Figure 5(a) shows the chargedischarge curves of PANIC-TiO

2-15 NTAs electrode at the current density of 01 02

05 1 and 2mA cmminus2 As a comparison the chargedischargecurves of C-TiO

2 PANIC-TiO

2-15 and PANIC-TiO

2-30 at

01mA cmminus2 are shown in Figure 5(b) Their specific capaci-tances are calculated according to the formula as follows

119862

119860=

119862

119860

=

119868 times Δ119905

Δ119881 times 119860

(1)

where119862119860is the specific capacitance 119868 is the chargedischarge

current density Δ119905 is the discharge time Δ119881 is the potentialrange and 119860 denotes apparent area of the electrode Thespecific capacitance of PANIC-TiO

2-15 NTAs is calculated

to be 1208 1193 1161 1117 and 1043mF cmminus2 at a currentdensity of 01 02 05 1 and 2mA cmminus2 shown in Figure 5(c)In contrast the specific capacitance of C-TiO

2and PANIC-

TiO2-30 NTAs is calculated to be 161 145 135 125 and

123mF cmminus2 and 2024 1638 1098 899 and 797mF cmminus2 atthe corresponding current density respectively It can be seenthat both PANIC-TiO

2-15 and PANIC-TiO

2-30 NTAs show

enhanced performance after the electropolymerization It isworth mentioning that the specific capacitance of PANIC-TiO2-30 NTAs is higher than that of the PANIC-TiO

2-

15 NTAs at a lower current density because of the largeamount of the loading mass of PANI per cm2 Howeverwhen the current density increases to 05mA cmminus2 the arealcapacitance becomes smaller than the PANIC-TiO

2-15NTAs

due to the poor ion diffusion in blocked nanotube of thePANIC-TiO

2-30

Cycling performance is also one of the most importantproperties of supercapacitor Cycling test of PANIC-TiO

2-

15 NTAs electrode was carried out at a current density of02mA cmminus2 in 1M H

2SO4solution in the potential range

of 0ndash06V (versus SCE) Figure 5(d) shows the curve ofcapacitance changes with the cycle number increasing After5000 cycles the capacitance retention is as high as 887Thisexcellent cycle stability of PANIC-TiO

2-15 NTAs electrode

resulted from the structure stability of C-TiO2NTAs during

charge-discharge process

4 Conclusions

In summary the PANIC-TiO2NTAs electrode was pre-

pared by depositing PANI on the conductive C-TiO2NTAs

obtained fromdirectly annealing the as-anodized TiO2NTAs

under Ar atmosphere The PANIC-TiO2-15 NTAs electrode

performs a good specific capacitance of 1208mF cmminus2 andgood rate ability with capacitance retention of 863 whenthe current density increases 20 times Due to the struc-ture stability of C-TiO

2NTAs PANIC-TiO

2nanocomposite

electrode expresses wonderful cycling performance that thespecific capacitance remains 887 even after 5000 cyclesAll these outstanding performances make this compositematerial a promising electrode in the field of energy storage


0 200 400 600 800 1000 1200 1400

00

01

02

03

04

05

06

Time (s)

Pote

ntia

l (V

ver

sus S

CE)

01mA cmminus2

02mA cmminus2

05mA cmminus2

1mA cmminus2

2mA cmminus2

(a)

0 500 1000 1500 2000 2500

00

01

02

03

04

05

06

Time (s)

(3)(2)

(3)

(1)

Pote

ntia

l (V

ver

sus S

CE)


PANIC-TiO2-30

2C-TiO

(b)

00 05 10 15 200

40

80

120

160

200

(3)

(2)

(1)

Current density (mA cmminus2)

Spec

ific c

apac

itanc

e (m

F cm

minus2)

(3)


PANIC-TiO2-30

2C-TiO

(c)

0 1000 2000 3000 4000 50000

20

40

60

80

100

Cycle number

Rent

entio

n (

)

(d)

Figure 5 (a) Chargedischarge curves of PANIC-TiO2-15 at different current densities of 01 02 05 1 and 2mA cmminus2 (b) Chargedischarge

curves of C-TiO2 PANIC-TiO

2-15 and PANIC-TiO

2-30 at 01mA cmminus2 (c) Rate performance of C-TiO

2 PANIC-TiO

2-15 and PANIC-

TiO2-30 (d) Cycling performance of the PANIC-TiO

2-15 electrode at a current density of 02mA cmminus2 in 1M H

2SO4

Conflict of Interests

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

Authorsrsquo Contribution

Chengcheng Zhang and Changjian Peng contributed equallyto this work

Acknowledgments

This work was financially supported by Young Scientificand Technological Backbone Cultivating Project of WuhanUniversity of Science and Technology (no 2013xz002)

the Outstanding Young and Middle-Aged Scientific Innova-tion Team of Colleges and Universities of Hubei Province(T201402) theNatural Science Foundation ofHubei Province(2013CFB327) and the Applied Basic Research Program ofWuhan City (2013011801010598)

References

[1] C Liu F Li L PMa andHM Cheng ldquoAdvancedmaterials forenergy storagerdquoAdvancedMaterials vol 22 no 8 pp E28ndashE622010

[2] H Wang H Feng and J Li ldquoGraphene and graphene-likelayered transition metal dichalcogenides in energy conversionand storagerdquo Small vol 10 no 11 pp 2165ndash2181 2014


[3] J Yan Q Wang T Wei and Z Fan ldquoRecent advances in designand fabrication of electrochemical supercapacitors with highenergy densitiesrdquo Advanced Energy Materials vol 4 no 4Article ID 1300816 2014

[4] G Yu X Xie L Pan Z Bao andYCui ldquoHybrid nanostructuredmaterials for high-performance electrochemical capacitorsrdquoNano Energy vol 2 no 2 pp 213ndash234 2013

[5] A L M Reddy S R Gowda M M Shaijumon and P MAjayan ldquoHybrid nanostructures for energy storage applica-tionsrdquo Advanced Materials vol 24 no 37 pp 5045ndash5064 2012

[6] J Yan T Wei B Shao et al ldquoPreparation of a graphenenanosheetpolyaniline composite with high specific capaci-tancerdquo Carbon vol 48 no 2 pp 487ndash493 2010

[7] C Peng D Hu and G Z Chen ldquoTheoretical specific capac-itance based on charge storage mechanisms of conductingpolymers comment on lsquoVertically oriented arrays of polyanilinenanorods and their super electrochemical propertiesrsquordquoChemicalCommunications vol 47 no 14 pp 4105ndash4107 2011

[8] X Y Zhao J B Zang Y H Wang L Y Bian and J K YuldquoElectropolymerizing polyaniline on undoped 100 nmdiamondpowder and its electrochemical characteristicsrdquo Electrochem-istry Communications vol 11 no 6 pp 1297ndash1300 2009

[9] L Xiao Y Cao J Xiao et al ldquoA soft approach to encapsulatesulfur polyaniline nanotubes for lithium-sulfur batteries withlong cycle liferdquo Advanced Materials vol 24 no 9 pp 1176ndash11812012

[10] J Yan T Wei Z Fan et al ldquoPreparation of graphene nano-sheetcarbon nanotubepolyaniline composite as electrodematerial for supercapacitorsrdquo Journal of Power Sources vol 195no 9 pp 3041ndash3045 2010

[11] E Frackowiak V Khomenko K Jurewicz K Lota and FBeguin ldquoSupercapacitors based on conducting polymersnano-tubes compositesrdquo Journal of Power Sources vol 153 no 2 pp413ndash418 2006

[12] X Yan Z Tai J Chen and Q Xue ldquoFabrication of carbonnanofiber-polyaniline composite flexible paper for supercapac-itorrdquo Nanoscale vol 3 no 1 pp 212ndash216 2011

[13] K Zhang L L Zhang X S Zhao and J Wu ldquoGraphenepoly-aniline nanofiber composites as supercapacitor electrodesrdquoChemistry of Materials vol 22 no 4 pp 1392ndash1401 2010

[14] W Wang and E A Schiff ldquoPolyaniline on crystalline siliconheterojunction solar cellsrdquo Applied Physics Letters vol 91 no13 Article ID 133504 2007

[15] K Xie J Li Y Lai et al ldquoPolyaniline nanowire array encapsu-lated in titania nanotubes as a superior electrode for superca-pacitorsrdquo Nanoscale vol 3 no 5 pp 2202ndash2207 2011

[16] K Siuzdak M Sawczak and A Lisowska-Oleksiak ldquoFabrica-tion and properties of electrode material composed of orderedtitania nanotubes and pEDOTPSSrdquo Solid State Ionics vol 271pp 56ndash62 2015

[17] X Peng K Huo J Fu X Zhang B Gao and P K Chu ldquoCoaxialPANITiNPANI nanotube arrays for high-performance super-capacitor electrodesrdquoChemical Communications vol 49 no 86pp 10172ndash10174 2013

[18] X Peng K Huo J Fu et al ldquoPorous dual-layered MoO119909

nanotube arrays with highly conductive TiN cores for superca-pacitorsrdquo ChemElectroChem vol 2 no 4 pp 512ndash517 2015

[19] L Hu K Huo R Chen B Gao J Fu and P K Chu ldquoRecy-clable and high-sensitivity electrochemical biosensing platformcomposed of carbon-doped TiO

2nanotube arraysrdquo Analytical

Chemistry vol 83 no 21 pp 8138ndash8144 2011

[20] X Peng J Fu X Zhang et al ldquoCarbon-doped TiO2nanotube

array platform for visible photocatalysisrdquo Nanoscience andNanotechnology Letters vol 5 no 12 pp 1251ndash1257 2013

[21] I C Kang Q Zhang S Yin T Sato and F Saito ldquoPreparationof a visible sensitive carbon doped TiO

2photo-catalyst by

grinding TiO2with ethanol and heating treatmentrdquo Applied

Catalysis B Environmental vol 80 no 1-2 pp 81ndash87 2008[22] L Zhang M S Tse O K Tan Y X Wang and M Han ldquoFacile

fabrication and characterization of multi-type carbon-dopedTiO2for visible light-activated photocatalytic mineralization of

gaseous toluenerdquo Journal of Materials Chemistry A vol 1 no 14pp 4497ndash4507 2013

[23] J Kan R Lv and S Zhang ldquoEffect of ethanol on propertiesof electrochemically synthesized polyanilinerdquo Synthetic Metalsvol 145 no 1 pp 37ndash42 2004

[24] Z Wang S Liu P Wu and C Cai ldquoDetection of glucose basedon direct electron transfer reaction of glucose oxidase immo-bilized on highly ordered polyaniline nanotubesrdquo AnalyticalChemistry vol 81 no 4 pp 1638ndash1645 2009

[25] V Khomenko E Frackowiak and F Beguin ldquoDeterminationof the specific capacitance of conducting polymernanotubescomposite electrodes using different cell configurationsrdquo Elec-trochimica Acta vol 50 no 12 pp 2499ndash2506 2005

Submit your manuscripts athttpwwwhindawicom

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Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


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MaterialsJournal of


Nano

materials


Journal ofNanomaterials


[15 16] However TiO2with poor conductivity hinders

electrodepositing PANI and goes against the rate ability ofsupercapacitor In very recently we improved the conduc-tivity of TiO

2by directly nitriding TiO

2NTAs to form well

conductive TiNNTAs acting as support materials for loadingPANI and MoOx which exhibits high specific capacitanceand excellent cycle stability [17 18]

In this work we demonstrated another conductive sup-port material carbon doped TiO

2nanotube arrays (C-TiO

2

NTAs) to maintain the PANI structure PANI can be easilydeposited on the surface to form uniform PANI and C-TiO

2

nanotube arrays (PANIC-TiO2NTAs) by the electrochem-

ical deposition Because of directional channel for electronstransport and the suitable tube space for the electrolytepermeating the PANIC-TiO

2NTAs electrode exhibits high

specific capacitance of 1208mF cmminus2 at the current densityof 01mA cmminus2 and it also remains 863 when the cur-rent density increases to 2mA cmminus2 It expresses wonderfulcycling performance with the specific capacitance retentionof 887 even after 5000 cycles The results demonstratethat the synthesized PANIC-TiO

2NTAs nanocomposite has

great potential applications for SCs

2 Experimental Details

All chemicals used are of analytical grade Electrochemicalanodization was adopted for TiO

2preparation with a typical

two-electrode configuration of electrochemical anodizationwhere a piece of Ti foil (1sdot1sdot05 cm3) was used as anodeand a piece of graphite plate was served as cathode with1 cm separation powered by a direct current power sup-ply (IT6834 ITECH China) The electrolyte was NH

4F

(05 wt) CH3OH (5 vol) and deionized water (5 vol)

in ethylene glycol The applied potential was 60V and lastedfor 30min

To produce the C-TiO2NTAs we developed an easy

annealing processing by utilizing the residual organic agencyafter anodization in ethylene glycol based electrolyte Indetail the as-anodized TiO

2NTAs was directly calcined in

a tube furnace at 500∘C for 3 h in Ar atmosphere with theheating rate of 15∘Cmin [19 20]

Controlled electropolymerization was used in a three-electrode system with a Pt foil (2sdot2 cm2) as the counterelectrode saturated calomel electrode (SCE) as the referenceelectrode TiO

2NTAs and C-TiO

2NTAs as the working

electrode to fabricate the composite NTAs In general theC-TiO

2NTAs was used as working electrode which was

subjected to repeating potential scanning in 05M H2SO4

solution containing 005M aniline in the range from minus06to 10 V at the scan rate of 50mVs for 15 and 30 cyclesrespectively

The samples were characterized by SEM (FE-SEM FEINova 400Nano) X-ray diffraction (XRD Philips X1015840 Pert Pro)with Cu K120572 radiation of wavelength of 15416 A in the rangeof 20ndash80∘ (2120579) FTIR Spectrometer (Perkin Elmer 1600)and X-ray photoelectron spectroscopy (ESCALB MK-II VGInstruments UK)

Electrochemical measurements were carried out using aCHI 660C instrument The three-electrode cell consisted ofa SCE as the reference electrode a 2sdot2 cm2 platinum plate asthe counter electrode and PANIC-TiO

2sample (1sdot1 cm2) as

the working electrode 1MH2SO4solution served as the elec-

trolyte at room temperature The cyclic voltammetry (CV)was performed between 0 and 1V (versus SCE) at differentscanning rate Galvanostatic charge-discharge curves weremeasured at different current density over the voltage rangeof 0ndash06V (versus SCE) Cycling stability performance wasconducted with a charge-discharge tester (Land CT2001AWuhan LAND Electronics Co Ltd China)

3 Results and Discussion

Figures 1(a) and 1(b) show the SEM images of TiO2NTAs and

C-TiO2NTAs obtained from annealing as-anodized TiO

2

NTAs under air and Ar respectively It is obvious that themorphologies of TiO

2NTAs and C-TiO

2NTAs are of no

significant difference The as-obtained highly ordered andwell-separated C-TiO

2NTAs have a length of about 9 120583m

interior diameter of about 110 nm and tube wall thicknessof about 20ndash25 nm As the XRD pattern of TiO

2NTAs and

C-TiO2NTAs shown in Figure 1(c) the diffraction peaks can

be attributed to anatase TiO2and titanium substrate and no

distinguished difference is observed between the TiO2NTAs

(1) and C-TiO2NTAs (2) Figure 1(d) displays the XPS full

spectra for TiO2NTAs (1) and C-TiO

2NTAs (2) C Ti and

O peaks are observed for C-TiO2NTAs while only Ti and O

peaks are observed for TiO2NTAsThe top right corner inset

shows the high-resolution C 1s spectra The peak at 2819 andweak peak at 2846 eV are attributed to Ti-C and C-C [21]The XPS results indicate that carbon was doped into the TiO

2

NTAs through the residual ethylene glycol reacting with theas-anodized amorphous TiO

2during annealing in Ar While

during heating in air the residual ethylene glycol can reactwith O

2forming CO

2and H

2O resulting in formatting pure

TiO2NTAs Figures 1(e) and 1(f) show the electrochemical

impedance spectroscopy of TiO2NTAs and C-TiO

2NTAs

respectively to identify their conductivity Compared to theresistance of the TiO

2NTAs (20 kΩ) the resistance of C-TiO

2

NTAs decreased by 3 orders of magnitude to 18Ω It indicatesthat the C-TiO

2NTAs has an excellent conductivity which

will be of benefit for aniline monomer electropolymerizingon tube wall

Figures 2(a) and 2(b) show the SEM images of thePANI deposited on TiO

2NTAs and C-TiO

2NTAs by elec-

tropolymerization in 005M aniline sulfuric acid solutionfor 15 cycles named PANITiO

2-15 and PANIC-TiO

2-15

respectively The typical PANIC-TiO2-15 nanotube has a

smaller interior diameter of 80 nm and its tube wall is 35ndash40 nm which is thicker than that of the C-TiO

2NTAs due

to the PANI depositing However for the PANITiO2-15

the diameter and tube wall are the same as the origin TiO2

nanotube The inset is corresponding electrochemical CVcurves of the PANI deposition process of them As for C-TiO2NTAs obvious redox peaks were observed and the peak

current increases with the cycle number increasing which


500nm

2120583m

(a)

500nm

2120583m

(b)

20 30 40 50 60 70 80

(2)

(1)

Inte

nsity

(au

)

2120579 (deg)

TiO2

Ti

(c)


C-TiC-C

286 284 282 280

t = 10min

(1)

C1s

Ti L

MM

1Ti

LM

MO

KLL Ti

2sO

1s

Ti3s Ti3p

(2)

Ti2

P 32

Ti2

P 12

minus400minus200

Inte

nsity

(au

)

(d)

0 8000 16000 24000 32000

0

4000

8000

12000

16000

Z998400 (ohm)

minusZ998400998400

(ohm

)

TiO2

(e)

0 20 40 60 80

0

20

40

60

80

100

120

140

Z998400 (ohm)

minusZ998400998400

(ohm

)

C-TiO2

(f)





2NTAs (e) and C-TiO

2NTAs (f) in 1M

H2SO4solution


500nm



minus08 minus04

Curr

ent (

A)

(a)

500nm



Curr

ent (

A)

minus08 minus04

(b)

500nm

(c)








2-30 is shown in








2


2



2500 2000 1500 1000 500

1263

1561

1350

(2)

(1)

813

1168

1220

1349

1483

1599

1600


Tran

smitt

ance

()


2

00 02 04 06 08 10

0

10

20

30

00 02 04 06 08 10minus10

minus05

000510

(2) D

CBA

(1)

A998400B998400 C998400 D998400

minus10


Curr

ent (

mA

cmminus2)


2C-TiO


Curr

ent (

mA

cmminus2)


2-15 at a scan rate

of 50mV sminus1



2SO4








2 PANIC-TiO

2-15 and PANIC-TiO

2-30 at


119862

119860=

119862

119860

=

119868 times Δ119905

Δ119881 times 119860

(1)





2and PANIC-



2-15 and PANIC-TiO

2-30 NTAs show


2-


2-15NTAs


2-30


2-




2-15 NTAs electrode



4 Conclusions






2NTAs PANIC-TiO

2nanocomposite



0 200 400 600 800 1000 1200 1400

00

01

02

03

04

05

06

Time (s)

Pote

ntia

l (V

ver

sus S

CE)

01mA cmminus2

02mA cmminus2

05mA cmminus2

1mA cmminus2

2mA cmminus2

(a)

0 500 1000 1500 2000 2500

00

01

02

03

04

05

06

Time (s)

(3)(2)

(3)

(1)

Pote

ntia

l (V

ver

sus S

CE)


PANIC-TiO2-30

2C-TiO

(b)

00 05 10 15 200

40

80

120

160

200

(3)

(2)

(1)


Spec

ific c

apac

itanc

e (m

F cm

minus2)

(3)


PANIC-TiO2-30

2C-TiO

(c)

0 1000 2000 3000 4000 50000

20

40

60

80

100

Cycle number

Rent

entio

n (

)

(d)



2-15 and PANIC-TiO


2 PANIC-TiO

2-15 and PANIC-



2SO4





Acknowledgments



References



























2photo-catalyst by















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




500nm

2120583m

(a)

500nm

2120583m

(b)

20 30 40 50 60 70 80

(2)

(1)

Inte

nsity

(au

)

2120579 (deg)

TiO2

Ti

(c)


C-TiC-C

286 284 282 280

t = 10min

(1)

C1s

Ti L

MM

1Ti

LM

MO

KLL Ti

2sO

1s

Ti3s Ti3p

(2)

Ti2

P 32

Ti2

P 12

minus400minus200

Inte

nsity

(au

)

(d)

0 8000 16000 24000 32000

0

4000

8000

12000

16000

Z998400 (ohm)

minusZ998400998400

(ohm

)

TiO2

(e)

0 20 40 60 80

0

20

40

60

80

100

120

140

Z998400 (ohm)

minusZ998400998400

(ohm

)

C-TiO2

(f)





2NTAs (e) and C-TiO

2NTAs (f) in 1M

H2SO4solution


500nm



minus08 minus04

Curr

ent (

A)

(a)

500nm



Curr

ent (

A)

minus08 minus04

(b)

500nm

(c)








2-30 is shown in








2


2



2500 2000 1500 1000 500

1263

1561

1350

(2)

(1)

813

1168

1220

1349

1483

1599

1600


Tran

smitt

ance

()


2

00 02 04 06 08 10

0

10

20

30

00 02 04 06 08 10minus10

minus05

000510

(2) D

CBA

(1)

A998400B998400 C998400 D998400

minus10


Curr

ent (

mA

cmminus2)


2C-TiO


Curr

ent (

mA

cmminus2)


2-15 at a scan rate

of 50mV sminus1



2SO4








2 PANIC-TiO

2-15 and PANIC-TiO

2-30 at


119862

119860=

119862

119860

=

119868 times Δ119905

Δ119881 times 119860

(1)





2and PANIC-



2-15 and PANIC-TiO

2-30 NTAs show


2-


2-15NTAs


2-30


2-




2-15 NTAs electrode



4 Conclusions






2NTAs PANIC-TiO

2nanocomposite



0 200 400 600 800 1000 1200 1400

00

01

02

03

04

05

06

Time (s)

Pote

ntia

l (V

ver

sus S

CE)

01mA cmminus2

02mA cmminus2

05mA cmminus2

1mA cmminus2

2mA cmminus2

(a)

0 500 1000 1500 2000 2500

00

01

02

03

04

05

06

Time (s)

(3)(2)

(3)

(1)

Pote

ntia

l (V

ver

sus S

CE)


PANIC-TiO2-30

2C-TiO

(b)

00 05 10 15 200

40

80

120

160

200

(3)

(2)

(1)


Spec

ific c

apac

itanc

e (m

F cm

minus2)

(3)


PANIC-TiO2-30

2C-TiO

(c)

0 1000 2000 3000 4000 50000

20

40

60

80

100

Cycle number

Rent

entio

n (

)

(d)



2-15 and PANIC-TiO


2 PANIC-TiO

2-15 and PANIC-



2SO4





Acknowledgments



References



























2photo-catalyst by















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




500nm



minus08 minus04

Curr

ent (

A)

(a)

500nm



Curr

ent (

A)

minus08 minus04

(b)

500nm

(c)








2-30 is shown in








2


2



2500 2000 1500 1000 500

1263

1561

1350

(2)

(1)

813

1168

1220

1349

1483

1599

1600


Tran

smitt

ance

()


2

00 02 04 06 08 10

0

10

20

30

00 02 04 06 08 10minus10

minus05

000510

(2) D

CBA

(1)

A998400B998400 C998400 D998400

minus10


Curr

ent (

mA

cmminus2)


2C-TiO


Curr

ent (

mA

cmminus2)


2-15 at a scan rate

of 50mV sminus1



2SO4








2 PANIC-TiO

2-15 and PANIC-TiO

2-30 at


119862

119860=

119862

119860

=

119868 times Δ119905

Δ119881 times 119860

(1)





2and PANIC-



2-15 and PANIC-TiO

2-30 NTAs show


2-


2-15NTAs


2-30


2-




2-15 NTAs electrode



4 Conclusions






2NTAs PANIC-TiO

2nanocomposite



0 200 400 600 800 1000 1200 1400

00

01

02

03

04

05

06

Time (s)

Pote

ntia

l (V

ver

sus S

CE)

01mA cmminus2

02mA cmminus2

05mA cmminus2

1mA cmminus2

2mA cmminus2

(a)

0 500 1000 1500 2000 2500

00

01

02

03

04

05

06

Time (s)

(3)(2)

(3)

(1)

Pote

ntia

l (V

ver

sus S

CE)


PANIC-TiO2-30

2C-TiO

(b)

00 05 10 15 200

40

80

120

160

200

(3)

(2)

(1)


Spec

ific c

apac

itanc

e (m

F cm

minus2)

(3)


PANIC-TiO2-30

2C-TiO

(c)

0 1000 2000 3000 4000 50000

20

40

60

80

100

Cycle number

Rent

entio

n (

)

(d)



2-15 and PANIC-TiO


2 PANIC-TiO

2-15 and PANIC-



2SO4





Acknowledgments



References



























2photo-catalyst by















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




2500 2000 1500 1000 500

1263

1561

1350

(2)

(1)

813

1168

1220

1349

1483

1599

1600


Tran

smitt

ance

()


2

00 02 04 06 08 10

0

10

20

30

00 02 04 06 08 10minus10

minus05

000510

(2) D

CBA

(1)

A998400B998400 C998400 D998400

minus10


Curr

ent (

mA

cmminus2)


2C-TiO


Curr

ent (

mA

cmminus2)


2-15 at a scan rate

of 50mV sminus1



2SO4








2 PANIC-TiO

2-15 and PANIC-TiO

2-30 at


119862

119860=

119862

119860

=

119868 times Δ119905

Δ119881 times 119860

(1)





2and PANIC-



2-15 and PANIC-TiO

2-30 NTAs show


2-


2-15NTAs


2-30


2-




2-15 NTAs electrode



4 Conclusions






2NTAs PANIC-TiO

2nanocomposite



0 200 400 600 800 1000 1200 1400

00

01

02

03

04

05

06

Time (s)

Pote

ntia

l (V

ver

sus S

CE)

01mA cmminus2

02mA cmminus2

05mA cmminus2

1mA cmminus2

2mA cmminus2

(a)

0 500 1000 1500 2000 2500

00

01

02

03

04

05

06

Time (s)

(3)(2)

(3)

(1)

Pote

ntia

l (V

ver

sus S

CE)


PANIC-TiO2-30

2C-TiO

(b)

00 05 10 15 200

40

80

120

160

200

(3)

(2)

(1)


Spec

ific c

apac

itanc

e (m

F cm

minus2)

(3)


PANIC-TiO2-30

2C-TiO

(c)

0 1000 2000 3000 4000 50000

20

40

60

80

100

Cycle number

Rent

entio

n (

)

(d)



2-15 and PANIC-TiO


2 PANIC-TiO

2-15 and PANIC-



2SO4





Acknowledgments



References



























2photo-catalyst by















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 200 400 600 800 1000 1200 1400

00

01

02

03

04

05

06

Time (s)

Pote

ntia

l (V

ver

sus S

CE)

01mA cmminus2

02mA cmminus2

05mA cmminus2

1mA cmminus2

2mA cmminus2

(a)

0 500 1000 1500 2000 2500

00

01

02

03

04

05

06

Time (s)

(3)(2)

(3)

(1)

Pote

ntia

l (V

ver

sus S

CE)


PANIC-TiO2-30

2C-TiO

(b)

00 05 10 15 200

40

80

120

160

200

(3)

(2)

(1)


Spec

ific c

apac

itanc

e (m

F cm

minus2)

(3)


PANIC-TiO2-30

2C-TiO

(c)

0 1000 2000 3000 4000 50000

20

40

60

80

100

Cycle number

Rent

entio

n (

)

(d)



2-15 and PANIC-TiO


2 PANIC-TiO

2-15 and PANIC-



2SO4





Acknowledgments



References



























2photo-catalyst by















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



























2photo-catalyst by















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 fabrication of pani/c-tio composite ...pani and moox, which exhibits high speci c...

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