)JOEBXJ1VCMJTIJOH$PSQPSBUJPO …downloads.hindawi.com/journals/jnm/2015/724064.pdf · Research Article Electrochemical Activity of a La 0.9 Ca 0.1 Co 1 x Fe x O 3 Catalyst for a Zinc

Research ArticleElectrochemical Activity of a La09Ca01Co1minusxFexO3 Catalyst fora Zinc Air Battery Electrode

Seungwook Eom1 Seyoung Ahn2 and Sanghwan Jeong1

1Battery Research Center Korea Electrotechnology Research Institute (KERI) 12 Bulmosan-ro 10 Beon-gil Seongsan-guChangwon 642-120 Republic of Korea2Battery Tech Center LG Chem Daejeon 104-1 Republic of Korea

Correspondence should be addressed to Seungwook Eom sweomkerirekr

Received 29 December 2014 Revised 13 March 2015 Accepted 13 March 2015

Academic Editor Shijun Liao

Copyright copy 2015 Seungwook Eom 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

The optimum composition of cathode catalyst has been studied for rechargeable zinc air battery applicationLa09Ca01Co1minusxFexO3 (119909 = 0ndash04) perovskite powders were prepared using the citrate method The substitution ratio of

Co2+ with Fe3+ cations was controlled in the range of 0ndash04 The optimum substitution ratio of Fe3+ cations was determinedby electrochemical measurement of the air cathode composed of the catalyst polytetrafluoroethylene (PTFE) binder andVulcan XC-72 carbon The substitution by Fe enhanced the electrochemical performances of the catalysts Considering oxygenreductionevolution reactions and cyclability we achieved optimum substitution level of 119909 = 01 in La

09Ca01Co1minusxFexO3

1 Introduction

The oxygen evolution reaction (OER) and the oxygen reduc-tion reaction (ORR) in aqueous solutions occur at a highoverpotential (119864(O

2gen) gt 119864(O2red)) This irreversibility ofthe reactions is the main problem for developing a cathodeof zinc air battery In addition bifunctional catalysts for thecathode are an important prerequisite for developing zinc airsecondary batteries Many types of electrocatalysts have beeninvestigated for the ORR and OER perovskite spinel noblemetal and pyrochlore [1ndash6] However most of the catalystscannot provide suitable performance for both the OER andORR A transition metal oxide can be used only for an ORRcatalyst whilemetal oxide and spinel compounds can be usedfor OER catalysts

Compared with noble metal catalysts metal oxides offerthe advantages of avoiding gassing on the zinc electrodewhen acting as bifunctional electrodes for the ORR and OER[7 8] The noble metal catalysts Pd Ag and Pt exhibit goodperformance for the ORR however these catalysts undergoa sharp degradation in the OER caused by the dissolution ofthe catalysts [9]

Perovskites which have the general formula ABO3

exhibit excellent catalytic performance in the ORR and OERbecause of their high oxide ion mobility Partial substitutionof A or B by a cation A1015840 or B1015840 with a different valence leadsto ionic defects or changes in the valence state of the catalystwhich affects the catalytic activity and conductivity of the cat-alyst [1]The substitution at catalytically active ldquoBrdquo sites in theABO3structure by some transition metal cation can enhance

the catalytic activity by leading to valence changes whichcauses non-stoichiometry-related microstructural defects inthe lattice [10] Therefore changing the oxygen content leadsto structural rearrangement increasing the lattice vacanciesleads to higher oxide ion mobility the synergistic role ofmixed valence states of cations at ldquoBrdquo sites and the segrega-tion of active metal components at the surface layer [10 11]

Fe-doped perovskite-type complex oxides exhibitexcellent electron-ion mixed conductivity therefore manyresearch groups are interested in these materials for elec-trode applications [12ndash16] In particular because thesematerials exhibit electric conductivities over 102Ωminus1sdotcmminus1and ionic conductivities of 10minus2ndash10Ωminus1sdotcmminus1 over800∘C Fe-doped perovskite-type complex oxides have

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2015 Article ID 724064 6 pageshttpdxdoiorg1011552015724064

2 Journal of Nanomaterials

Mixing

Grinding

Vacuum drying

Catalyst

Citric acid + H2O

La(NO3)3middot6H2OCa(NO3)2middot4H2O

Fe(NO3)3middot9H2O

Stirring and heating (90∘C)

Heating (100ndash120∘C)

Calcination (700∘C 2 h)

Figure 1 Manufacturing process of the cathode catalyst

attracted growing attention [17] Shimizu et al synthesizedLa1minusxA1015840

119909Co1minusyB1015840

119910O3(A1015840 Ca B1015840 Mn Fe Ni and Cu) using

the citrate method and reported that the perovskite catalystsexhibited the best performance for the ORR and cyclabilitywhen the Co cation was substituted by a Fe cation [18]

In a previous investigation La09Ca01Co1minusxFexO3 (119909 =

0ndash04) oxides were synthesized and applied to the cathode forzinc air secondary batteries These catalysts exhibited excel-lent electrochemical properties at room temperature [19]

2 Experimental

La09Ca01Co1minusxFexO3 (119909 = 0ndash04) oxide was synthe-

sized using the citrate method for the cathode cata-lyst of zinc air secondary batteries As starting materi-als La(NO

3)2sdot6H2O Ca(NO

3)2sdot4H2O Co(NO

3)2sdot6H2O and

Fe(NO3)3sdot9H2O were used Metal nitrates were mixed in

a stoichiometric molar ratio of La09Ca01Co1minusxFexO3 (119909 =

0ndash04) and dissolved in deionized water Then citric acidwas added as a chelating agent while stirring constantlyAfter mixing the starting materials the solution containinga mixture of citric acid and constituent metal nitrates washeated at 90∘C for several hours to evaporate the excess sol-vents and promote polymerization When the gel precursorwas attained it was heated at 100ndash120∘C until it burned upfollowed by calcination for 2 hours at 700∘C (Figure 1)

The air electrode was prepared as illustrated in Figure 2First a polytetrafluoroethylene (PTFE) dispersion (60Dupont 30-J) was mixed with deionized water and ultra-sonically dispersed for 10min Vulcan XC-72 carbon blackand prepared La

09Ca01Co1minusxFexO3 (119909 = 0ndash04) perovskite

catalyst powder were poured into the PTFE-water mixture

The mixture was stirred for 2 h and dried at 120∘C Thedried electrode powder was mixed again with some drops ofisopropyl alcohol and kneaded to make a cathode sheet usinga roll press This cathode sheet was attached to one side of aNi mesh and a PTFE sheet for the gas diffusion electrode wasplaced at the other side of the Ni mesh Figure 2 shows theprocess for preparing the air electrode The compositions ofthe air cathode were 425 La

09Ca01Co1minusxFexO3 (119909 = 0ndash04)

perovskite 425 Vulcan XC-72 carbon black and 15 PTFEdispersion

The prepared disk-type cathode was used as a workingelectrode and was placed into an electrochemical cell On theopposite side the platinum mesh as a counter electrode wasplaced with an HgHgO electrode as the reference electrodeAn 85M potassium hydroxide (KOH) solution was used asthe electrolyte

A potentiostat (VMP3 Princeton Applied Research) wasused for electrochemical measurement of the half-cell Thescan rate for the linear sweep voltammograms (LSV) andcyclic voltammograms (CV) was 2mV sminus1 and 5mV sminus1respectively

The surface morphology of the cathode was examinedusing a scanning electron microscope (S-2700 HitachiJapan) The XRD patterns were obtained using an X-raydiffractometer (1830 X-ray diffractometer Philips) using Ni-filtered CuK120572 radiation (120582 = 15406 A) in the 2120579 range of 20∘ndash90∘ at a scan rate of 01∘ sminus1

3 Results and Discussion

Based on the XRD analysis presented in Figure 3 we verifiedthat the powder calcined at 700∘C contained a single phase of

Journal of Nanomaterials 3

Vulcan XC-72

Catalyst

Dehydrated mixture

Paste

Ultrasonic homogenizing

Isopropyl alcohol

Sheet

Kneading

Cathode

Ni mesh

PTFE dispersion + H2O

Mixing (1 h)

Drying (120∘C)

Figure 2 Manufacturing process of the cathode

20 30 40 50

P

P

P P P P P

60 70 80 90

Inte

nsity

P perovskite

X = 00

X = 01

X = 02

X = 03

X = 04

2120579

Figure 3 XRD patterns of La09Ca01Co1minusxFexO3 (119909 = 0ndash04) catalyst after calcination

La09Ca01CoO3perovskite structures in all of the Fe-doped

levels Figure 4 shows the representative morphology of theLa09Ca01Co1minusxFexO3 (119909 = 0ndash04) catalysts The powders

exhibit an average particle size of 50 nm (primary particles)Figures 5 and 6 present the polarization curves for a series

of Fe-doped perovskites La09Ca01Co1minusxFexO3 (119909 = 0ndash04)

The substitutions of cobalt cations by iron cations couldimprove the catalytic activity thus reduced cathodic over-potentials were obtained with the Fe-doped La

09Ca01CoO3

cathode comparedwith the nondopedmaterials Neburchilovet al reported that the Fe-doped perovskite catalyst has highactivity for the decomposition of the HO

2

minus in the two-electron pathway in ORR that occurred in alkaline solution

[6 20] Similar results were observed for the anodic polar-ization characteristics as demonstrated in Figure 6 Consid-ering the cathodic and anodic polarization characteristicsthe optimum composition based on the Fe doping level wasLa09Ca01Co09Fe01O3

As observed in Figures 5 and 6 the doping ofLa09Ca01CoO3with Fe could lead to improvements in the

oxygen evolution reaction rather than the oxygen reductionreaction According to the results obtained by Jorissenwell-crystallized materials improve the oxygen reductionreaction whereas less crystalline materials are beneficial forthe oxygen evolution reaction [9] The particle size of thesynthesized Fe-doped La

09Ca01CoO3was approximately


Figure 4 SEM images of catalyst

00

01

0 50 100 150 200 250minus05

minus04

minus03

minus02

minus01

Pote

ntia

l (V

ver

sus H

gH

gO)

x = 01

x = 02

x = 00 x = 03

x = 04

Current density (mA cmminus2)

Figure 5 Cathodic polarization curves of La09Ca01Co1minusxFexO3

(119909 = 0ndash04) cathodes

00

01

02

03

04

05

06

07

0 50 100 150 200 250

Pote

ntia

l (V

ver

sus H

gH

gO)

x = 01

x = 02

x = 00 x = 03

x = 04


Figure 6 Anodic polarization curves of La09Ca01Co1minusxFexO3 (119909 =

0ndash04) cathodes

30 nm which was smaller than that of the non-Fe-dopedLa09Ca01CoO3 and the XRD intensity of the Fe-doped

La09Ca01CoO3was smaller Therefore it can be concluded

that the Fe-doped La09Ca01CoO3alloys synthesized in

00

02

04

06

08

0 50 100 150 200 250


x = 01

x = 02

x = 00 x = 03

x = 04

Pote

ntia

l (V

ver

sus H

gH

gO)

minus04

minus06

minus02

ΔE[E(O2 gen) minus E(O2 red)] 50 mAcm2-x = 00 ≒ 929 mV-x = 01 ≒ 712 mV-x = 02 ≒ 717 mV-x = 03 ≒ 725 mV-x = 04 ≒ 735 mV

Figure 7 Anodic and cathodic polarization curves ofLa09Ca01Co1minusxFexO3 (119909 = 00ndash04) cathodes

000

03

04

05

06

07

08

0 01 02 03 04minus025

minus020

minus015

minus010

minus005

Ano

dic p

olar

izat

ion

Cath

odic

pol

ariz

atio

npo

tent

ial

50

mA

cmminus

2(V

)

x in La09Ca01Co1minusxFexO3

pote

ntia

l 5

0m

A cm

minus2

(V)

Figure 8 Anodic and cathodic polarization potentials at currentdensity of 50mA cmminus2 as a function of Fe doping level

this study were less crystalline Therefore these alloys werebeneficial for the oxygen evolution reaction

WhenCo in the La09Ca01CoO3is substitutedwith Fe the

lattice contains non-stoichiometry-related microstructuraldefects due to synergistic valence changes Therefore thecatalytic activity may be improved However high contentsof Fe lead to decreased ion mobility because the bindingenergy of Fe-O is stronger than that of Co-O [12] Therefore


0

50

00 05 10Potential (V versus HgHgO)

minus05minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co09Fe01O3

(a)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co08Fe02O3

Potential (V versus HgHgO)

(b)

00 05 10minus05

0

50

minus150

minus200

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co07Fe03O3


(c)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co06Fe04O3


(d)

Figure 9 Cyclic voltammograms of La09Ca01Co1minusxFexO3 cathode at a sweep rate of 5mV sminus1 (a) 119909 = 01 (b) 119909 = 02 (c) 119909 = 03 and

(d) 119909 = 04

as illustrated in Figures 5-6 highly Fe-doped La09Ca01CoO3

exhibits a larger cathodic or anodic overpotentialFigures 7 and 8 present the anodic and cathodic polariza-

tion curves of La09Ca01Co1minusxFexO3 (119909 = 01ndash04) catalysts

as a function of the Fe doping level In these results thepotential differences between charging (oxygen evolution119894 = 50mA cmminus2) and discharging (oxygen reduction 119894 =50mA cmminus2) were 929mV for 119909 = 00 712mV for 119909 = 01717mV for 119909 = 02 725mV for 119909 = 03 and 735mV for119909 = 04

The fact that the substitutions of cobalt with iron couldimprove the catalytic activity was demonstrated by sev-eral observations However as observed in Figure 9 uponincreasing the Fe content the cyclabilityworsened whichwascaused by degradation of the structural properties of the cath-ode during cycling Oxygen reduction can take place throughtwo pathways One leads to water or OHminus through a four-electron reduction the other one leads to peroxide througha two-electron reduction It is known that the perovskitecatalyst has four-electron pathway reaction however at highcurrent density region it follows two-electron pathway as thefollowing two steps

O2+H2O + 2eminus = H

2Ominus +OHminus (first step)

H2Ominus + 2eminus +H

2O = 3HOminus (second step)

(1)

The peroxide formed during the two-electron reactiondiffuses into the bulk solution During diffusion the peroxide

oxidizes the Teflon bonding between the catalyst and carbonDecomposition of Teflon bonding blocks the cathode poreand results in increment of internal resistance This is themain reason of capacity degradation [6] It is presumed thatthe two-electron path ratio is increased alongwith the dopinglevel of Fe in La

09Ca01Co1minusxFexO3 Therefore the cathode

structure becomes unstable

4 Conclusions

To improve the catalytic activity Co in La09Ca01CoO3was

substituted with Fe In the anodic and cathodic polarizationmeasurements the substitution by Fe enhanced the elec-trochemical performances of the catalysts due to synergis-tic valence changes and resultant non-stoichiometry-relatedmicrostructural defects introduced into the lattice Howeverhighly Fe-doped La

09Ca01Co1minusxFexO3 lost their structural

stabilityOverall by simultaneously considering oxygen

reductionevolution reactions and cyclabilityLa09Ca01Co09Fe01O3could be applied as a good bifunc-

tional catalyst for cathodes

Conflict of Interests

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


Acknowledgment

This work was supported by the National Research Foun-dation of Korea grant funded by the Korean Government(MEST) (NRF-2012-M1A2A2-028739)

References

[1] O Haas F Holzer K Muller and S Muller Handbook of FuelCells Fundamentals Technology Applications John Wiley ampSons 2003

[2] N-LWuW-R Liu and S-J Su ldquoEffect of oxygenation on elec-trocatalysis of La

06Ca04CoO3minus119909

in bifunctional air electroderdquoElectrochimica Acta vol 48 no 11 pp 1567ndash1571 2003

[3] S Royer F Berube and S Kaliaguine ldquoEffect of the synthesisconditions on the redox and catalytic properties in oxidationreactions of LaCo

1minus119909Fe119909O3rdquo Applied Catalysis A General vol

282 no 1-2 pp 273ndash284 2005[4] W-D Yang Y-H Chang and S-H Huang ldquoInfluence of

molar ratio of citric acid to metal ions on preparation ofLa067Sr033

MnO3materials via polymerizable complex pro-

cessrdquo Journal of the European Ceramic Society vol 25 no 16pp 3611ndash3618 2005

[5] C Xiulan and L Yuan ldquoNew methods to prepare ultrafineparticles of some perovskite-type oxidesrdquoChemical EngineeringJournal vol 78 no 2-3 pp 205ndash209 2000

[6] V Neburchilov H Wang J J Martin and W Qu ldquoA review onair cathodes for zinc-air fuel cellsrdquo Journal of Power Sources vol195 no 5 pp 1271ndash1291 2010

[7] O Haas F Holzer S Muller et al ldquoX-ray absorption anddiffraction studies of La

06Ca04CoO3perovskite a catalyst for

bifunctional oxygen electrodesrdquo Electrochimica Acta vol 47 no19 pp 3211ndash3217 2002

[8] V Hermann D Dutriat S Muller and C Comninellis ldquoMech-anistic studies of oxygen reduction at La

06Ca04CoO3-activated

carbon electrodes in a channel flow cellrdquo Electrochimica Actavol 46 no 2-3 pp 365ndash372 2000

[9] L Jorissen ldquoBifunctional oxygenair electrodesrdquo Journal ofPower Sources vol 155 no 1 pp 23ndash32 2006

[10] H Tanaka and M Misono ldquoAdvances in designing perovskitecatalystsrdquo Current Opinion in Solid State amp Materials Sciencevol 5 no 5 pp 381ndash387 2001

[11] M R Pai B N Wani B Sreedhar S Singh and NM Gupta ldquoCatalytic and redox properties of nano-sizedLa08Sr02Mn1minusxFexO3minus120575 mixed oxides synthesized by different

routesrdquo Journal of Molecular Catalysis A Chemical vol 246 no1-2 pp 128ndash135 2006

[12] L-W Tai M M Nasrallah H U Anderson D M Spar-lin and S R Sehlin ldquoStructure and electrical properties ofLa1minusxSrxCo1minusyFeyO3 Part 1 The system La

08Sr02Co1minusyFeyO3rdquo

Solid State Ionics vol 76 no 3-4 pp 259ndash271 1995[13] M Petitjean G Caboche E Siebert L Dessemond and L

Dufour ldquo(La08Sr02)(Mn1minus119910

Fe119910)O3plusmn120575

oxides for ITSOFC cath-ode materials Electrical and ionic transport propertiesrdquo Jour-nal of the European Ceramic Society vol 25 pp 2651ndash26542005

[14] S Canulescu T Lippert A Wokaun et al ldquoPreparation ofepitaxial La

06Ca04Mn1minus119909

Fe119909O3(119909 = 0 02) thin films variation

of the oxygen contentrdquo Progress in Solid State Chemistry vol 35no 2ndash4 pp 241ndash248 2007

[15] V Dayal and S Keshri ldquoStructural and magnetic properties ofLa067

Ca033

Mn(1minus119909)

FexO3(x = 0ndash007)rdquo Solid State Communica-

tions vol 142 no 1-2 pp 63ndash66 2007[16] F Tietz I Arul Raj M Zahid and D Stover ldquoElectrical con-

ductivity and thermal expansion of La08Sr02(MnFeCo)O

3minus120575

perovskitesrdquo Solid State Ionics vol 177 no 19ndash25 pp 1753ndash17562006

[17] Q Xu D-P Huang W Chen J-H Lee H Wang and R-ZYuan ldquoCitrate method synthesis characterization and mixedelectronic-ionic conduction properties of La

06Sr04Co08Fe02O3

perovskite-type complex oxidesrdquo Scripta Materialia vol 50 no1 pp 165ndash170 2004

[18] Y Shimizu H Matsuda N Miura and N Yamazoe ldquoBi-functional oxygen electrode using large surface area perovskite-type oxide catalyst for rechargeable metal-air batteriesrdquo Chem-istry Letters vol 21 no 6 pp 1033ndash1036 1992

[19] S-W Eom S-Y Ahn I-J Kim Y-K Sun andH-S Kim ldquoElec-trochemical evaluation of La

1minus119909Ca119909CoO3cathode material for

zinc air batteries applicationrdquo Journal of Electroceramics vol 23no 2ndash4 pp 382ndash386 2009

[20] J Garche Encyclopedia of Electrochemical Power Sources vol 4Elsevier 2009

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


Mixing

Grinding

Vacuum drying

Catalyst

Citric acid + H2O

La(NO3)3middot6H2OCa(NO3)2middot4H2O

Fe(NO3)3middot9H2O

Stirring and heating (90∘C)

Heating (100ndash120∘C)

Calcination (700∘C 2 h)

Figure 1 Manufacturing process of the cathode catalyst

attracted growing attention [17] Shimizu et al synthesizedLa1minusxA1015840

119909Co1minusyB1015840

119910O3(A1015840 Ca B1015840 Mn Fe Ni and Cu) using

the citrate method and reported that the perovskite catalystsexhibited the best performance for the ORR and cyclabilitywhen the Co cation was substituted by a Fe cation [18]

In a previous investigation La09Ca01Co1minusxFexO3 (119909 =

0ndash04) oxides were synthesized and applied to the cathode forzinc air secondary batteries These catalysts exhibited excel-lent electrochemical properties at room temperature [19]

2 Experimental

La09Ca01Co1minusxFexO3 (119909 = 0ndash04) oxide was synthe-

sized using the citrate method for the cathode cata-lyst of zinc air secondary batteries As starting materi-als La(NO

3)2sdot6H2O Ca(NO

3)2sdot4H2O Co(NO

3)2sdot6H2O and

Fe(NO3)3sdot9H2O were used Metal nitrates were mixed in

a stoichiometric molar ratio of La09Ca01Co1minusxFexO3 (119909 =

0ndash04) and dissolved in deionized water Then citric acidwas added as a chelating agent while stirring constantlyAfter mixing the starting materials the solution containinga mixture of citric acid and constituent metal nitrates washeated at 90∘C for several hours to evaporate the excess sol-vents and promote polymerization When the gel precursorwas attained it was heated at 100ndash120∘C until it burned upfollowed by calcination for 2 hours at 700∘C (Figure 1)

The air electrode was prepared as illustrated in Figure 2First a polytetrafluoroethylene (PTFE) dispersion (60Dupont 30-J) was mixed with deionized water and ultra-sonically dispersed for 10min Vulcan XC-72 carbon blackand prepared La

09Ca01Co1minusxFexO3 (119909 = 0ndash04) perovskite

catalyst powder were poured into the PTFE-water mixture

The mixture was stirred for 2 h and dried at 120∘C Thedried electrode powder was mixed again with some drops ofisopropyl alcohol and kneaded to make a cathode sheet usinga roll press This cathode sheet was attached to one side of aNi mesh and a PTFE sheet for the gas diffusion electrode wasplaced at the other side of the Ni mesh Figure 2 shows theprocess for preparing the air electrode The compositions ofthe air cathode were 425 La

09Ca01Co1minusxFexO3 (119909 = 0ndash04)

perovskite 425 Vulcan XC-72 carbon black and 15 PTFEdispersion

The prepared disk-type cathode was used as a workingelectrode and was placed into an electrochemical cell On theopposite side the platinum mesh as a counter electrode wasplaced with an HgHgO electrode as the reference electrodeAn 85M potassium hydroxide (KOH) solution was used asthe electrolyte

A potentiostat (VMP3 Princeton Applied Research) wasused for electrochemical measurement of the half-cell Thescan rate for the linear sweep voltammograms (LSV) andcyclic voltammograms (CV) was 2mV sminus1 and 5mV sminus1respectively

The surface morphology of the cathode was examinedusing a scanning electron microscope (S-2700 HitachiJapan) The XRD patterns were obtained using an X-raydiffractometer (1830 X-ray diffractometer Philips) using Ni-filtered CuK120572 radiation (120582 = 15406 A) in the 2120579 range of 20∘ndash90∘ at a scan rate of 01∘ sminus1

3 Results and Discussion

Based on the XRD analysis presented in Figure 3 we verifiedthat the powder calcined at 700∘C contained a single phase of


Vulcan XC-72

Catalyst

Dehydrated mixture

Paste


Isopropyl alcohol

Sheet

Kneading

Cathode

Ni mesh


Mixing (1 h)

Drying (120∘C)


20 30 40 50

P

P

P P P P P

60 70 80 90

Inte

nsity

P perovskite

X = 00

X = 01

X = 02

X = 03

X = 04

2120579







09Ca01CoO3


2








00

01

0 50 100 150 200 250minus05

minus04

minus03

minus02

minus01

Pote

ntia

l (V

ver

sus H

gH

gO)

x = 01

x = 02

x = 00 x = 03

x = 04




00

01

02

03

04

05

06

07

0 50 100 150 200 250

Pote

ntia

l (V

ver

sus H

gH

gO)

x = 01

x = 02

x = 00 x = 03

x = 04



0ndash04) cathodes




00

02

04

06

08

0 50 100 150 200 250


x = 01

x = 02

x = 00 x = 03

x = 04

Pote

ntia

l (V

ver

sus H

gH

gO)

minus04

minus06

minus02



000

03

04

05

06

07

08

0 01 02 03 04minus025

minus020

minus015

minus010

minus005

Ano

dic p

olar

izat

ion

Cath

odic

pol

ariz

atio

npo

tent

ial

50

mA

cmminus

2(V

)


pote

ntia

l 5

0m

A cm

minus2

(V)






0

50


minus05minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co09Fe01O3

(a)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co08Fe02O3


(b)

00 05 10minus05

0

50

minus150

minus200

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co07Fe03O3


(c)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co06Fe04O3


(d)


(d) 119909 = 04










(1)





4 Conclusions










Acknowledgment


References



























Fe119910)O3plusmn120575







Ca033

Mn(1minus119909)




3minus120575



06Sr04Co08Fe02O3














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Vulcan XC-72

Catalyst

Dehydrated mixture

Paste


Isopropyl alcohol

Sheet

Kneading

Cathode

Ni mesh


Mixing (1 h)

Drying (120∘C)


20 30 40 50

P

P

P P P P P

60 70 80 90

Inte

nsity

P perovskite

X = 00

X = 01

X = 02

X = 03

X = 04

2120579







09Ca01CoO3


2








00

01

0 50 100 150 200 250minus05

minus04

minus03

minus02

minus01

Pote

ntia

l (V

ver

sus H

gH

gO)

x = 01

x = 02

x = 00 x = 03

x = 04




00

01

02

03

04

05

06

07

0 50 100 150 200 250

Pote

ntia

l (V

ver

sus H

gH

gO)

x = 01

x = 02

x = 00 x = 03

x = 04



0ndash04) cathodes




00

02

04

06

08

0 50 100 150 200 250


x = 01

x = 02

x = 00 x = 03

x = 04

Pote

ntia

l (V

ver

sus H

gH

gO)

minus04

minus06

minus02



000

03

04

05

06

07

08

0 01 02 03 04minus025

minus020

minus015

minus010

minus005

Ano

dic p

olar

izat

ion

Cath

odic

pol

ariz

atio

npo

tent

ial

50

mA

cmminus

2(V

)


pote

ntia

l 5

0m

A cm

minus2

(V)






0

50


minus05minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co09Fe01O3

(a)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co08Fe02O3


(b)

00 05 10minus05

0

50

minus150

minus200

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co07Fe03O3


(c)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co06Fe04O3


(d)


(d) 119909 = 04










(1)





4 Conclusions










Acknowledgment


References



























Fe119910)O3plusmn120575







Ca033

Mn(1minus119909)




3minus120575



06Sr04Co08Fe02O3














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





00

01

0 50 100 150 200 250minus05

minus04

minus03

minus02

minus01

Pote

ntia

l (V

ver

sus H

gH

gO)

x = 01

x = 02

x = 00 x = 03

x = 04




00

01

02

03

04

05

06

07

0 50 100 150 200 250

Pote

ntia

l (V

ver

sus H

gH

gO)

x = 01

x = 02

x = 00 x = 03

x = 04



0ndash04) cathodes




00

02

04

06

08

0 50 100 150 200 250


x = 01

x = 02

x = 00 x = 03

x = 04

Pote

ntia

l (V

ver

sus H

gH

gO)

minus04

minus06

minus02



000

03

04

05

06

07

08

0 01 02 03 04minus025

minus020

minus015

minus010

minus005

Ano

dic p

olar

izat

ion

Cath

odic

pol

ariz

atio

npo

tent

ial

50

mA

cmminus

2(V

)


pote

ntia

l 5

0m

A cm

minus2

(V)






0

50


minus05minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co09Fe01O3

(a)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co08Fe02O3


(b)

00 05 10minus05

0

50

minus150

minus200

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co07Fe03O3


(c)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co06Fe04O3


(d)


(d) 119909 = 04










(1)





4 Conclusions










Acknowledgment


References



























Fe119910)O3plusmn120575







Ca033

Mn(1minus119909)




3minus120575



06Sr04Co08Fe02O3














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0

50


minus05minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co09Fe01O3

(a)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co08Fe02O3


(b)

00 05 10minus05

0

50

minus150

minus200

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co07Fe03O3


(c)

00 05 10minus05

0

50

minus150

minus100

minus50

Curr

ent d

ensit

y (m

A cm

minus2)

La09Ca01Co06Fe04O3


(d)


(d) 119909 = 04










(1)





4 Conclusions










Acknowledgment


References



























Fe119910)O3plusmn120575







Ca033

Mn(1minus119909)




3minus120575



06Sr04Co08Fe02O3














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Acknowledgment


References



























Fe119910)O3plusmn120575







Ca033

Mn(1minus119909)




3minus120575



06Sr04Co08Fe02O3














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



Documents

)JOEBXJ1VCMJTIJOH$PSQPSBUJPO …downloads.hindawi.com/journals/jnm/2015/724064.pdf · Research Article Electrochemical Activity of a La 0.9 Ca 0.1 Co 1 x Fe x O 3 Catalyst for a Zinc