research article development of membraneless sodium

Research ArticleDevelopment of Membraneless Sodium Perborate Fuel Cell forMedia Flexible Power Generation

K Ponmani1 S Durga1 A Arun1 S Kiruthika2 and B Muthukumaran1

1 Department of Chemistry Presidency College Chennai 600 005 India2Department of Chemical Engineering SRM University Chennai 603 203 India

Correspondence should be addressed to B Muthukumaran drmuthukumaranyahoocom

Received 19 November 2013 Revised 8 January 2014 Accepted 9 January 2014 Published 27 March 2014

Academic Editor Mohamed Mohamedi

Copyright copy 2014 K Ponmani et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

This paper reports the media flexibility of membraneless sodium perborate fuel cell (MLSPBFC) using acidalkaline bipolarelectrolyte in which the anode is in acidic media while the cathode is in alkaline media or vice versa Investigation of the celloperation is conducted by using formic acid as a fuel and sodium perborate as an oxidant for the first time under ldquoacid-alkalinemediardquo configurations The MLSPBFC architecture enables interchangeable operation with different media combinations Theexperimental results indicate that operating under ldquoacid-alkalinemediardquo conditions significantly improves the fuel cell performancecompared with all-acidic and all-alkaline conditions The effects of flow rates and the concentrations of various species at both theanode and cathode on the cell performance are also investigated It has been demonstrated that the laminar flow basedmicrofluidicmembraneless fuel cell can reach amaximum power density of 282mWcmminus2 with a fuel mixture flow rate of 03mLminminus1 at roomtemperature

1 Introduction

The portable multifunctional electronic devices with highspeed operations necessitate better energy storage and supplyoptions that deliver increased power and energy densityCurrent battery technologies appear to be approaching aperformance plateau insufficient to meet the needs of futuredevices Portable fuel cells while being a battery alternativethat shows good potential to meet future needs have yet toresolve a number of technical challenges As a result severalmicrofabrication techniques are developed to increase thepower density becauseminiaturization of fuel cells stacks andcomponents increases the electrochemically active surfacearea to volume ratio which is an important consideration toimprove performance

A novel microfabrication methodmdashfabrication insidecapillaries using multistream laminar flowmdashprovided theidea for a new type of fuel cell which eliminates several ofthe technical issues related to the use of proton exchangemembrane fuel cells (PEMFCs) such as fuel crossover [1]membrane degradation long startup time ohmic lossessize fabrication and water management limited durability of

catalysts [2] A membrane as used in membrane-electrodeassemblies (MEAs) brings about a resistance to the transportof ions through the electrolytes Furthermore MEAs areexpensive components at presentTherefore the cell structurewithout the membrane has two merits decrease of electricalresistivity in the cell and inexpensive material cost

A membraneless fuel cell is a device that does notcontain membrane and it converts chemical energy froma fuel and an oxidant into electric energy by means ofoxidoreduction reactions It eliminates the above problems ofPEMFCs associated with membranes Membraneless microfuel cells use liquid reactants (fuel and oxidant) that flow sideby side in a laminar fashion in a single channel without amembrane Anode and cathode electrodes are positioned onthe opposing channelwalls and themixing of fuel and oxidantin the channel occurs only by diffusion Apart from theconventional fuel cells (PEMFCs) the membraneless microfuel cell does not need anode or cathode humidification andmaintains the water level in the cell because flowing streamcan automatically remove water out of the cell As a resultthe water management is not needed [3] Furthermore thestructures of membraneless micro fuel cells are very simple

Hindawi Publishing CorporationInternational Journal of ElectrochemistryVolume 2014 Article ID 962161 9 pageshttpdxdoiorg1011552014962161

2 International Journal of Electrochemistry

Table 1 Theoretical open-circuit potential and maximum efficiency of various fuels

Fuel Reaction 119899 (e) minusΔ119867∘ (kJmol) minusΔ119866∘ (kJmol) 119864rev∘ (V) Maximum efficiency ()

Ethanol CH3CH2OH + 3O2 rarr 2CO2 + 3H2O 12 2777 1749 115 6298Hydrogen H2 + 12 O2 rarr H2O 2 286 2373 123 8297V2+ V2+ + VO2+ + 2H+

rarr V3+ + VO2+ + H2O 1 4318 4042 119 9361Methanol CH3OH + 12 O2 rarr CO2 + 2H2O 6 7266 7025 121 9668Formic acid HCOOH + 12 O2 rarr CO2 + 2H2O 2 2703 2855 148 1056

and easy to miniaturize [4] so that light and stackable fuelcells can be fabricated with simple microelectromechanicalsystems (MEMS) [5 6] The flexibility and the performanceimplications of operating membraneless sodium perboratefuel cell (MLSPBFC) under ldquoacid-alkaline mediardquo that is oneelectrode is acidic and the other one is alkaline condition willbe the focus of this study

Recent catalysis and fuel cell research has indicated thatformic acid may be a good alternative to the commonfuels of hydrogen and methanol [7 8] Even though formicacid has a lower energy density than methanol 749 and175 JmL respectively the possibility for a significant increasein performance with the correct catalyst exists [9] Comparedto hydrogen and methanol formic acid has a higher overalltheoretical open circuit potential and maximum efficiencyas indicated in Table 1 In sum formic acid seems to be apromising fuel for fuel cells and thus will be explored as thefuel with the membraneless fuel cell in this paper

However since the previous researchers used oxygensolution as the oxidant the performance of these micro fuelcells was found to be restricted severely by the low transportefficiency of oxygen in the cathode stream

In this communication for the first time we introducesodium perborate (NaBO

3

sdot 4H2

O) as an oxidant underldquoacid-alkaline mediardquo to demonstrate the performance ofa membraneless sodium perborate fuel cell (MLSPBFC)Sodium perborate is a true peroxo salt and is a convenientsource of hydrogen peroxide [10 11]

[B(OH)3

(O2

H)]minus +H2

O 999445999468 [B(OH)4

]minus

+H2

O2

(1)

The sodium perborate fuel cell (MLSPBFC) is uniquefrom previous fuel cells using H

2

O2

as mentioned in ourearlier study sodium perborate can be used not only as anoxidant but also as a reductant [12 13]

TheMLSPBFChas some advantages for example sodiumperborate is a cheap nontoxic and large scale industrialchemical which is used primarily in detergents and as a mildoxidant [14] The cell being more environmentally friendlythan the other fuel cells and the sodium perborate canbe handled more simply than hydrogen as it is a well-known fact that sodium perborate solution is a widespreadsafe disinfectant On the performance side the MLSPBFCgenerates electric power comparable to a typical air-breathingDMFC when operated in a microchemical channel at roomtemperature In addition the MLSPBFC requires no mem-brane electrode assemblies Thus the cost for the materials islow and the structure of the cell is simple

Table 2 Summary of the theoretical energy densities for differentfuels

Fuel Gravimetric energydensity (Wh kgminus1)

Volumetric energydensity (WhLminus1)

Formic acid 2086 1710Sodium borohydride 2925 2840Methanol 4690 6400Ethanol 6100 7850

Since formic acid fuel cells are capable of deliveringhigher energy densities than the most competitive recharge-able batteries [15] and can easily be obtained from fossilfuels such as natural gas or coal as well as from existencesources through fermentation of agricultural products andfrom biomasses we use formic acid as a fuel to study theperformance of MLSPBFC in this work This is an importantmetric in the development of converged electronic devicesas the operating time is becoming limited by conventionalbattery technology Table 2 provides relevant data aboutthe alternative fuels and their theoretical energy densitiesThese fuels exhibit higher volumetric and gravimetric energydensities than batteries Many works are under progress onthe development of microfluidic direct formic acid fuel cells[16ndash19]

Moreover in recent years the effect of operating lam-inar flow based fuel cells in all-acidic all-alkaline andacidicalkaline medium is highly focused [20 21] Sincecertain hydrocarbons such as formic acid and methanol caneasily be stored in liquid form under ambient conditionsare known to give safer high energy densities As for theacidalkaline bipolar electrolyte Ayato et al used a polymer-electrolyte membrane consisting of acid and alkaline ion-exchange layers for a HFC [22] The function of their bipolarmembrane wasmainly to keep the power stable bymodifyingwater management On the other hand we use the bipolarelectrolyte to force reactions (3) and (5) to proceed Thusthe use of perborate in the acidalkaline bipolar electrolyteis characteristic of the MLSPBFC

In this study a new branch of simplified architectures thatis unique from those that have been reported in the literaturehas been developed by eliminating and integrating the keycomponents of a conventional MEA With these advantagesmembraneless sodium perborate fuel cells (MLSPBFC) canbe used as an alternative for portable power applications

International Journal of Electrochemistry 3

2 Experimental

21 Materials and Reagents The materials and chemicalsused during the tests are listed as follows HCOOH(98 Merck) NaBO

3

sdot4H2

O (99 Riedel) NaOH(98 Merck) and H

2

SO4

(98 Merck) PDMSpoly(dimethylsiloxane) (999 Chemsworth) and PMMApoly(methylmethacrylate) (92 G Khanna amp Co) graphiteplates (Kriti Graphite) and silicon tubes (Shree GauravRubber Products) All experiments were conducted at roomtemperature using formic acid in deionised water as a fueland sodium perborate in deionised water as an oxidantand 05M NaOH and 05M H

2

SO4

in deionised water aselectrolytes

22 Catalyst Deposition For all the experiments ofMLSPBFC unsupported platinum black nanoparticlesare applied to the sides of the graphite plates to act as cathodeand anode that line the microfluidic channel The catalystsuspensions for both anode and cathode were preparedby mixing at a concentration of 60mgmLminus1 Pt blacknanoparticles (Alpha Aesar) in a 10wt Nafion solution(Nafion stock solution Dupont 5 (119908119908) solution) Thismixture was sonicated and applied to the side faces of thegraphite plates at a loading of 2mg cmminus2 Then solvent wasevaporated by the use of a heat lamp for uniform loading

23 Design of Membraneless Sodium Perborate Fuel Cells(MLSPBFC) In the MLSPBFC configuration an E-shapedlaminar flow channel with catalyst-coated graphite platesof 1mm thickness is used After subsequent depositionof catalyst to the cathode and anode the E-shapedmicrofluidic channel structure is molded with PDMSpoly(dimethylsiloxane) typically 1ndash10mm in thickness andfinally sealed with a solid substrate such as 2mm thick piecesof PMMA poly(methylmethacrylate) to provide rigidity andsupportive strength to the layered system Silicon tubingis placed to guide the fuel and oxidant into the E-shapedchannel systems at the top and to guide the waste stream outat the bottom of the channel (Figure 1)

24 Test of the Fuel Cell The solutions of fuel and oxidantwere pumped through the device using a syringe pump(Schiller India) The flow rate of each of the streams was03mLminminus1 (total flow rate of 06mLminminus1) Also thecell was allowed to run for an hour for the flow to reacha steady state When injected through the inlets fuel andoxidant solutionswillmerge at the E-junction and continue toflow laminarly in parallel over the anode and cathode wherefuel and oxidant are allowed to be oxidized and reducedrespectively Cell measurements were conducted using aCS310 computer controlled potentiostat (ZhengzhouTriangleInstrument Co Ltd) with the associated Thales Z softwarepackage For each analysed factor the performance of thefuel cell was evaluated by recording the cell polarisation andobtaining the corresponding power density curves Conse-quently the microfluidic cell keeps these fluids stable withouta separation membrane

Cathode

Anode

Graphite

Oxidant

Fuel

Outlet

PMMA

Figure 1 Schematic of the E-shaped membraneless laminarflow based fuel cell with graphite plates molded with PDMSpoly(dimethylsiloxane) and sealed with PMMA poly(methylmetha-crylate)

25 Acid-Alkaline Media Flexibility of MLSPBFC This mem-braneless microfabrication method eliminates several of thetechnical issues related to the use of polymer electrolytemembrane fuel cells (PEMs) [23 24] In addition lack of amembrane also allows for operation of MLSPBFC in morethan onemediumMoreover the chemical composition of thecathode and anode streams can be designed individually tooptimize individual electrode kinetics as well as overall cellpotential Furthermore the MLSPBFC has the flexibility torun in all-acidic all-alkaline media or in an ldquoacid-alkalinemediardquo mode in which the anode is exposed to acidic mediawhile the cathode is exposed to alkaline media or viceversa The performance of MLSPBFC in acid-alkaline mediaconfiguration using an alkaline anode and an acidic cathoderesults in a higher overall cell potential than those obtainedfrom all-acidic and all-alkaline fuel cell experiments

3 Results and Discussion

Two different approaches have been pursued the first stepconsisted in the flexibility and the performance implica-tions of operating membraneless sodium perborate fuelcell (MLSPBFC) under ldquoacid-alkaline mediardquo configurationthe second step was intended to further improve the cellperformance by characterising themain cell by changing sev-eral operational parameters namely the fuelsrsquo compositionsoxidantsrsquo compositions electrolytesrsquo compositions distanceeffect and flow rate and to observe their influence on thepolarisation behaviour of the cell

31 Performance of MLSPBFC in All-Acidic and All-AlkalineMedia The pH of the electrolyte has an effect on reactionkinetics at the individual electrodes as well as the electrodepotential at which oxidation or reduction occurs [25ndash29]Equations (2) and (3) represent the half-cell reactions andstandard electrode potentials of formic acid oxidation andperoxide reduction in acidic media and (5) and (6) representthe alkaline media Equation (7) shows the overall cell


0 2 4 6 8 10 12

02

00

04

06

08

10

All-acidic

Pote

ntia

l (V

)

Current density (mA cmminus2)

(a)

0 2 4 6 8 10 12 14 16 18 20

All-alkaline

00

02

04

06

08

10

12

Pote

ntia

l (V

)


(b)

Figure 2 Polarisation curves for overall cell performance of MLSPBFC operating in (a) all-acidic and (b) all-alkaline media at roomtemperature For both experiments the fuel stream is 2M formic acid + 05M NaOH (a) and in 05M H

2

SO4

(b) and the oxidant streamis 01M perborate + 05M NaOH (a) and 05M H

2

SO4

(b) Stream flow rates 03mLminminus1

reaction in all-acid or all-alkaline media Both the alkaline-alkaline media and the acidic-acidic media have a maximumtheoretical open circuit potential (OCP) of 2156V and 156Vrespectively Consider the following

Formic acidperborate in acidic mediaAnode

HCOOH 997888rarr CO2

+ 2H+ + 2eminus 119864∘

= 022V (2)

Cathode

3H2

O2

+ 6H+ + 6eminus 997888rarr 6H2

O 119864∘

= 178V (3)

Overall reaction all-acidic media

HCOOH + 3H2

O2

+ 4H+ + 4eminus 997888rarr CO2

+ 6H2

O

119864∘

= 156V(4)

Formic acidperborate in alkaline mediaAnode

2HCOOminus + 6OHminus 997888rarr 2CO3

2minus

+ 4H2

O + 4eminus

119864∘

= minus117V(5)

Cathode

3H2

O2

+ 6eminus 997888rarr 6OHminus 119864∘

= 0986V (6)

Overall reaction all-alkaline media

2HCOOminus + 3H2

O2

+ 2eminus 997888rarr 2CO3

2minus

+ 4H2

O

119864∘

= 2156V(7)

A comparison of the performance of an MLSPBFCin all-acidic and all-alkaline media is exhibited in

Figures 2(a) and 2(b) respectively Initially at low currentdensities both the polarization curves are identical andthus the performance of MLSPBFC is independent of themedium The mass transport limitation region is around6mA cmminus2 in the MLSPBFC running for both alkaline andacidic media The MLSPBFC were run over several dayswithout any drop in their performance at a wide variety oftest conditions No issues with carbonate formation wereencountered in these MLSPBFC at room temperature as anycarbonate that does form is immediately removed from thesystem by the flowing streams

32 Performance of MLSPBFC in Acid-Alkaline Media1 Acidic Anode Alkaline Cathode The performance ofMLSPBFC using a fuel stream of 2M Formic acid in 05MH2

SO4

and an oxidant stream of 01M perborate in 05MNaOH was investigated The measurements were carried outat room temperature for two configurations acid-alkalinemedia 1 acidic anode alkaline cathode and acid-alkalinemedia 2 alkaline anode acidic cathode In these acid-alkalinemedia configurations the neutralization reaction of OHminus andH+ to water occurs at the liquid-liquid interface between thefuel and oxidant stream In the first configuration the overallcell reaction (10) can be obtained from (2) and (6)

Acid-alkaline media 1 acidic anode and alkaline cathodeAnode


+ 2H+ + 2eminus 119864∘

= 022V (8)

Cathode

H2

O2


= 0986V (9)


0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

MultimediaAll-alkaline

Pote

ntia

l (V

)

All-acidic


Figure 3 Polarisation curves of MLSPBFC with an alkaline anodeand acidic cathode (acid-alkaline media) at room temperature Forcomparison also the polarisation curves of theMLSPBFC run in all-alkaline and in all-acidicmedia are included [Fuel] 2M formic acid+ 05M NaOH [Oxidant] 01M perborate + 05M H

2

SO4

Streamflow rates 03mLminminus1

Overall

HCOOH + 3H2

O2

997888rarr CO2

+ 2H+ + 2OHminus

119864∘

= 0766V(10)

In this acid-alkalinemedia configuration 1 themaximumtheoretical OCP is 0766V The energy liberated in theformic acid oxidation and peroxide reduction reactions ismostly consumed by the water ionization reaction In thisconfiguration coexistence of the galvanic and methanolelectrolytic reactions has been found to be the reason forincapability of yielding useful amounts of energy and was notstudied any further

33 Performance of MLSPBFC in Acid-Alkaline Media 2Alkaline Anode Acidic Cathode In contrast in acid-alkalinemedia configuration 2 the MLSPBFC using a fuel stream ofan alkaline anode and an acidic cathode allows energy tobe obtained both from the formic acid oxidationperoxidereduction reactions and from the acidalkali electrochemicalneutralization reactions as evident from the overall cellreaction equation (13)

Acid-alkaline media 2 alkaline anode acidic cathodeAnode

HCOOminus + 3OHminus 997888rarr CO3

2minus

+ 2H2

O + 2eminus

119864∘

= minus117V(11)

Cathode

3H2

O2


O 119864∘

= 178V (12)

0

5

10

15

20

25

30

0 10 20 30 40 50 60 70Current density (mA cmminus2)

Pow

er d

ensit

y (m

W cm

minus2)

MultimediaAll-alkalineAll-acidic

Figure 4 Power density curves for overall cell performance ofMLSPBFC operating in alkaline (05M NaOH) acidic (05MH2

SO4

) and mixed-media (anode 05MNaOH and cathode 05MH2

SO4

) at room temperature For all experiments the fuel stream is2M formic acid and the oxidant stream is 01M perborate in therespective media Stream flow rates 03mL minminus1

Overall

HCOOminus + 3H2

O2

+ 6H+ + 3OHminus + 4eminus 997888rarr CO3

2minus

+ 8H2

O

119864∘

= 295V(13)

In this acid-alkaline media 2 configuration the com-bination of two galvanic reactions yields a desirable hightheoretical OCP of 295V Note that the inherent value of theelectromotive force of theMLSPBFC is higher than that of theHFC (123V) and the PEMFC or DMFC (121 V) Howeverbecause of the overpotentials resulting from the slow kineticsof peroxide reduction and formic acid oxidation the opencircuit potential is reduced to a measured value of 181 V(Figure 3) In the alkaline anodeacidic cathode acid-alkalinemedia configuration both OHminus and H+ are consumed at theanode and cathode respectively at a rate of two for eachmolecule of formic acid

Operating in this acid-alkaline media configuration withan alkaline anode and an acidic cathode resulted in a higheroverall cell potential than those obtained for the all-acidicand all-alkaline MLSPBFC experiments Figure 4 showsthe power density curves of the MLSPBFC experimentsperformed in different media combinations at the anode andcathode

In MLSPBFC the all-acidic and all-alkaline experimentshave maximum power densities of 281 and 60mWcmminus2respectively both at a cell potential of about 10 V whereasthe acid-alkalinemedia experiment results in a power densitymaximum of 282mWcmminus2 at a cell potential of about 10 V


Table 3 Effect of medium on the performance of the MLSPBFC

All-alkaline All-acidic Acid-alkaline media 2Open-circuit voltage (V) 116 093 181Short-circuit current density (mA cmminus2) 180 120 6246Peak power density (mWcmminus2) 60 281 282Cell voltage at peak power density (V) 050 038 071Current density at peak power density (mWcmminus2) 120 739 3985

00

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

20 M15 M10 M

05 M25 M

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)


Figure 5 Effect of formic acid concentration on the current andpower density of the MLSPBFC at room temperature [Fuel] 119909Mformic acid + 05M NaOH [Oxidant] 01M perborate + 05MH2

SO4

Stream flow rates 03mLminminus1

Within this condition the acid-alkalinemedia fuel cell clearlyoutperforms both the all acidic and all-alkaline fuel cell(Table 3) The higher power densities in the acid-alkalinemedia MLSPBFC are a direct result of higher overall cellpotentials due to the unprecedented ability to operate thecathode and anode at different pH in an MLSPBFC

34 Influence of Fuel Composition The effect of fuel on theperformance of MLSPBFC has been observed by varyingthe formic acid concentration between 05M and 25M(Figure 5)

When fuel concentration is high the limiting currentdensity and the maximum power density are larger As morereactants enter the cell the mass transport to the electrodesincreases Accordingly the current density and power densityincreases However the transport rate is limited by the deple-tion region [30] Thus the current density did not increasesignificantly while increasing the fuel concentrations beyond2M which also suggests that the performance of the mem-braneless fuel cells is limited by slow anodecathode kineticsor slow diffusion of reagents to the electrode surface due tothe formation of a concentration boundary layer From thiswe conclude that the concentration of formic acid as low as05M did not result in a reduction of the cell performance

00

02

04

06

08

10

12

14

16

18

20

0 10 20 30 40 50 60 700

5

10

15

20

25

30

Pote

ntia

l (V

)

0100 M0075 M0050 M

0025 M0010 M

Pow

er d

ensit

y (m

W cm

minus2)


Figure 6 Effect of perborate concentration on the current andpower density of the MLSPBFC at room temperature [Fuel] 2Mformic acid + 05M NaOH [Oxidant] 119909M perborate + 05MH2

SO4


which indicates that the cell is cathode limited [3] In thepresent study experimental results show that the fuel cellperformance is maximum at 2M and further increase in theformic acid concentration has no significant effect on the fuelcell

35 Influence of Oxidant Composition The effects of perbo-rate concentration on the cell performance were investigatedat 001 0025 005 0075 and 01M The power densityincreased in correlation to increased sodium perborate con-centration in MLSPBFC and reached the maximum of 181 Vat 01M sodium perborate Peak power densities of 228658 1210 1970 and 2821mWcmminus2 were obtained at 0010025 005 0075 and 01M respectively (Figure 6) Furtherincrease in the oxidant concentration shows no improvementin the cell performanceTherefore the value of 01M has beenfixed for the perborate concentration in the oxidant solution

The data of the exchange current density for anode andcathode also indicates that the activation losses are primarilydue to the lower chemical activity at cathode Accordinglywe may conclude that the cell performance well be enhancedprofoundly if the concentration of oxidant in cathodic stream


000002004

006008

010

0

5

10

15

20

25

30

0001

0203

0405

[Perborate]01 M0075 M0050 M

0025 M0010 M

[Perborate]

Pow

er d

ensit

y (m

W cm

minus2

)

[H 2SO 4

]

Figure 7 Effect of various combinations of perborate and sul-phuric acid concentrations on the maximum power density(282mWcmminus2) of the MLSPBFC at room temperature The fuelmixture for variation of oxidant is ([fuel] 2M formic acid + 05MNaOH [oxidant] 119909M perborate + 05M H

2

SO4

) and the fuelmixture for variation of sulphuric acid is ([fuel] 2M formic acid +05MNaOH [oxidant] 01M perborate + 119909MH

2

SO4

) Stream flowrates 03mLminminus1

can be increased to raise concentration flux or the exchangecurrent density at the cathode can bemade as high as possible

Likewise the effect of H2

SO4

compositions on the oxi-dant solution has also been analysed The H

2

SO4

concentra-tion was varied between 001M and 05M The maximumpower density (282mWcmminus2) was obtained at 05M H

2

SO4

(Figure 7) Further increase in the H2

SO4

concentrationshows no improvement in the cell performanceTherefore thevalue of 05M has been fixed for the H

2

SO4

concentration inthe oxidant solution

36 Influence of Distance Effect on the Performance ofMLSPBFC In order to find the potential benefit from areduced diffusion length of reacting species moving betweenthe anode and cathode the fuel cell test was conducted fordifferent distances between 1 and 100mmWhen the distancebetween the anode and cathode decreased the maximumpower density increased as shown in Figure 8 Consideringthe role of a charge carrier a shorter diffusion length isbelieved to give a faster electrochemical reaction becausethe diffusion time of reacting species would be shorterTherefore more reactions can take place at a given timewhich increases the total number of charges involving theelectrochemical reactions at the anode and cathode Thisfinding provides a good evidence of the presence of a chargecarrier moving between the anode and cathode in the fuelmixture to complete redox reactions of the fuel cell [31]

0 20 40 60 80 1000

5

10

15

20

25

30

Pow

er d

ensit

y (m

W cm

minus2)

Distance between the electrodes (mm2)

Figure 8 Effect of distance between anode and cathode on themaximum power density of the MLSPBFC at room temperature[Fuel] 2M formic acid + 05M NaOH [Oxidant] 01M perborate+ 05M H

2

SO4


37 Influence of Fuel Mixture Flow Rate Since maximumpower density is dependent on the transport time of reactingspecies it can be controlled by its flow rates In this exper-iment flow rates of 01 02 03 04 05 06 07 08 09and 10mLminminus1 were tested The cell potential and currentwere measured with different external loads as a function ofthe flow velocity of fuel mixture Using the flow rate appliedand the cross-sectional area of the channel a flow velocitycan be calculated In this work the maximum power densityis obtained at about 03mLminminus1 after that the maximumpower density decreases with increase in flow rate as shownin Figure 9 It is believed that more electrochemical reactionswould take place at a given time and a greater output currentcould develop in the end

38 Stability Test Durability of the MLSPBFC was examinedunder continuous test considering its practical applicationsShort-term stability of MLSPBFC under acid-alkaline mediaconfigurations was tested by monitoring the cell voltagechange during the galvanostatic discharge of 62mA cmminus2of the MLSPBFC in a period of about 100 h (Figure 10)The MLSPBFC maintained a relatively stable performancewith a little decay of cell voltage over the test period Thefluctuation in the cell voltage was due to addition of the newfuel solution restarting the experiments or small variation incell temperatureThe possible reasons for the gradual declinein cell performance with time may be due to the formationof Na

2

CO3

The result of the durability test showed thatthe MLSPBFC in our research has good stability at roomtemperature which is able to satisfy the necessary conditionsas portable power sources

4 Conclusions

A microscale membraneless sodium perborate fuel cell(MLSPBFC) was fabricated on PDMS and its performance


0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)

03 mL minminus1

02 mLminminus101 mL minus1min

min04 mL minus1

05 mL minminus1

06 mL minminus1min07 mL minus1

08 mL minminus1


Figure 9 Effect of flow rate of fuelmixture on the current and powerdensity of the MLSPBFC at room temperature [Fuel] 2M formicacid + 05M NaOH [Oxidant] 01M perborate + 05M H

2

SO4

20 40 60 80 10012

14

16

18

20

Pote

ntia

l (V

)

62mA cmminus2

Time (100h)

Figure 10 Performance stability of the MLSPBFC operating atcurrent density of 62mA cmminus2 at room temperature [Fuel] 2Mformic acid + 05M NaOH [Oxidant] 01M perborate + 05MH2

SO4


was evaluated under different operating conditions Standardmicrofabrication techniques were used to develop the deviceIn this membraneless fuel cell formic acid is used as a fuelat the anode and sodium perborate is used as an oxidant atthe cathode for the first time under ldquoacid-alkalinemediardquoTheexperiments described in this study show that membranelesssodium perborate fuel cells are media flexible they canbe operated in all-acidic all-alkaline or even acid-alkalinemedia configurations

In this work we observed that the alkaline anodeacidiccathode acid-alkaline media configuration leads to a very

high measured OCP of 181 V while other combinations willresult in very low OCPs as a result of the pH dependence ofstandard electrode potentials TheMLSPBFC operated in thealkaline anodeacidic cathode acid-alkalinemedia configura-tion the measured OCP of 181 V is in good agreement withthe theoretical OCP of 295V

At room temperature the laminar flow-based microflu-idic fuel cell produced a maximum power density of282mWcmminus2 under alkaline anodeacidic cathode acid-alkaline media configurations We concluded that acid-alkaline media MLSPBFC seems to outperform the all-acidic and all-alkaline MLSPBFC The effects of flow rates ofthe fuel and oxidant variation of concentrations of formicacid perborate and electrolytes were evaluated under acid-alkaline media configurations The performance was charac-terized by V-I curves and anode polarization plots

The results demonstrated that the performance of thedevelopedmembraneless fuel cell enhanced profoundly if theconcentration of oxidant in cathodic stream is 10 times largerand the current density is also increased approximately tentimes

Thus the present experimental findings have confirmedthat this membraneless micro fuel cell is cathode limitedand suggest that it is a crucial factor in improving cellperformance to increase the concentration of oxidant inthe cathodic stream The flexibility of membraneless fuelcells to function with different media allowed the successfuloperation of mixed alkaline and acidic fuel cells The mem-braneless micro fuel cell system investigated in this studyseems to be a good candidate for feasible application becauseits performance is comparable to an air-breathing DMFC

In addition the development of metal catalysts to accel-erate the efficiency of MLSPBFC is in progress Some furtherexperimental works towards themicrochannel design and theflow rate of MLSPBFC with various fuels will be beneficialto verify the present predictions and fulfill the practicalutilization in portable power sources

The MLSPBFC have the advantages of their miniaturesizes simplicity of fabrication use of aqueous fuel and goodcost efficiency Furthermore perborate is cheap nontoxicstable easily handled environment-friendly and large-scaleindustrial chemical and is a convenient source of hydrogenperoxide We expect that the MLSPBFC may be a promisingcandidate for practical fuel cells to establish a clean andsustainable energy future

Conflict of Interests

The authors declare that they have no conflict of interestsregarding the publication of this paper

Acknowledgment

Thefinancial support for this research fromUniversityGrantsCommission (UGC) New Delhi India through a MajorResearch Project 42-3252013 (SR) is gratefully acknowl-edged


References

[1] L Carrette K A Friedrich and U Stimming ldquoFuel cellsprinciples types fuels and applicationsrdquo ChemPhysChem vol1 no 4 pp 163ndash193 2000

[2] M Eikerling A A Kornyshev A M Kuznetsov J Ulstrup andS Walbran ldquoMechanisms of proton conductance in polymerelectrolyte membranesrdquo Journal of Physical Chemistry B vol105 no 17 pp 3646ndash3662 2002

[3] E R Choban L J Markoski A Wieckowski and P J A KenisldquoMicrofluidic fuel cell based on laminar flowrdquo Journal of PowerSources vol 128 no 1 pp 54ndash60 2004

[4] R S Jayashree LGancs E R Choban et al ldquoAir-breathing lam-inar low-based microfluidic fuel cellrdquo Journal of the AmericanChemical Society vol 127 no 48 pp 16758ndash16759 2005

[5] J L Cohen D A Westly A Pechenik and H D AbrunaldquoFabrication and preliminary testing of a planar membranelessmicrochannel fuel cellrdquo Journal of Power Sources vol 139 no1-2 pp 96ndash105 2005

[6] A Bazylak D Sinton and N Djilali ldquoImproved fuel utilizationin microfluidic fuel cells a computational studyrdquo Journal ofPower Sources vol 143 no 1-2 pp 57ndash66 2005

[7] M Weber J-T Wang S Wasmus and R F Savinell ldquoFormicacid oxidation in a polymer electrolyte fuel cell a real-timemass-spectrometry studyrdquo Journal of the Electrochemical Soci-ety vol 143 no 7 pp L158ndashL160 1996

[8] C Rice S Ha R I Masel P Waszczuk A Wieckowski and TBarnard ldquoDirect formic acid fuel cellsrdquo Journal of Power Sourcesvol 111 no 1 pp 83ndash89 2002

[9] G-Q Lu A Crown and A Wieckowski ldquoFormic acid decom-position on polycrystalline platinum and palladized platinumelectrodesrdquo Journal of Physical Chemistry B vol 103 no 44 pp9700ndash9711 1999

[10] F A Cotton and G Wilkinson Advanced Inorganic ChemistryWiley Interscience New York NY USA 1988

[11] C Karunakaran and B Muthukumaran ldquoMolybdenum(VI)catalysis of perborate or hydrogen peroxide oxidation of iodideionrdquo Transition Metal Chemistry vol 20 no 5 pp 460ndash4621995

[12] M Gowdhamamoorthi A Arun S Kiruthika and B Muthu-kumaran ldquoEnhanced performance of membraneless fuel cellsrdquoInternational Journal of ChemTech Research vol 5 no 3 pp1143ndash1151 2013

[13] M Gowdhamamoorthi A Arun S Kiruthika and B Muthu-kumaran ldquoEnhanced performance of membraneless sodiumpercarbonate fuel cellsrdquo Journal of Materials vol 2013 ArticleID 548026 7 pages 2013

[14] A Arun M Gowdhamamoorthi S Kiruthika and B Muthu-kumaran ldquoElectrocatalyzed oxidation of methanol on car-bon supported platinum electrode in membraneless sodiumpercarbonate fuel cells (MLSPCFC)rdquo International Journal ofChemTech Research vol 5 no 3 pp 1152ndash1161 2013

[15] J Yeom G Z Mozsgai A Asthana et al ldquoA silicon micro-fabricated direct formic acid fuel cellrdquo in Proceedings of the 1stInternational Conference on Fuel Cell Science Engineering andTechnology pp 267ndash272 April 2003

[16] G Q Lu C Y Wang T J Yen and X Zhang ldquoDevelopmentand characterization of a silicon-based micro direct methanolfuel cellrdquo Electrochimica Acta vol 49 no 5 pp 821ndash828 2004

[17] S C Kelley G A Deluga and W H Smyrl ldquoMiniaturemethanolair polymer electrolyte fuel cellrdquo Electrochemical andSolid-State Letters vol 3 no 9 pp 407ndash409 2000

[18] T Yen N Fang X Zhanga G Q Lu and C Y Wang ldquoA micromethanol fuel cell operating at near room temperaturerdquoAppliedPhysics Letters vol 83 p 4056 2003

[19] S Motokawa M Mohamedi T Momma S Shoji and TOsaka ldquoMEMS-based design and fabrication of a new conceptmicro direct methanol fuel cell (120583-DMFC)rdquo ElectrochemistryCommunications vol 6 no 6 pp 562ndash565 2004

[20] E R Choban J S Spendelow L Gancs A Wieckowski andP J A Kenis ldquoMembraneless laminar flow-based micro fuelcells operating in alkaline acidic and acidicalkaline mediardquoElectrochimica Acta vol 50 no 27 pp 5390ndash5398 2005

[21] J C Shyu C L Huang T S Sheu and H Ay ldquoExperimentalstudy of direct hydrogen peroxidemicrofluidic fuel cellsrdquoMicroamp Nano Letters IET vol 7 pp 740ndash743 2012

[22] Y Ayato T Okada and Y Yamazaki ldquoCharacterization ofbipolar ion exchange membrane for polymer electrolyte fuelcellsrdquo Electrochemistry vol 71 no 5 pp 313ndash317 2003

[23] E R Choban P Waszczuk L J Markoski A Wieckowski andP J A Kenis Rochester NY USA 2003

[24] E R Choban L J Markoski J Stoltzfus J S Moore and P JA Kenis ldquoMicrofluidic fuel cells that lack a polymer electrolytemembranerdquo in Power Sources Proceedings vol 40 pp 317ndash3202002

[25] J S Spendelow G Q Lu P J A Kenis and A WieckowskildquoElectrooxidation of adsorbedCOon Pt(1 1 1) and Pt(1 1 1)Ru inalkalinemedia and comparison with results from acidic mediardquoJournal of Electroanalytical Chemistry vol 568 no 1-2 pp 215ndash224 2004

[26] G F McLean T Niet S Prince-Richard and N DjilalildquoAn assessment of alkaline fuel cell technologyrdquo InternationalJournal of Hydrogen Energy vol 27 no 5 pp 507ndash526 2002

[27] T Iwasita ldquoElectrocatalysis of methanol oxidationrdquo Elec-trochimica Acta vol 47 no 22-23 pp 3663ndash3674 2002

[28] D R Lide CRCHandbook of Chemistry and Physics CRC PressLCC MARC Records Transmitter System 85th edition 2005

[29] E H Yu andK Scott ldquoDevelopment of directmethanol alkalinefuel cells using anion exchange membranesrdquo Journal of PowerSources vol 137 no 2 pp 248ndash256 2004

[30] H B Park K H Lee andH J Sung ldquoPerformance of H-shapedmembraneless micro fuel cellsrdquo Journal of Power Sources vol226 pp 266ndash271 2013

[31] W Sung and J-W Choi ldquoA membraneless microscale fuel cellusing non-noble catalysts in alkaline solutionrdquo Journal of PowerSources vol 172 no 1 pp 198ndash208 2007

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Table 1 Theoretical open-circuit potential and maximum efficiency of various fuels

Fuel Reaction 119899 (e) minusΔ119867∘ (kJmol) minusΔ119866∘ (kJmol) 119864rev∘ (V) Maximum efficiency ()

Ethanol CH3CH2OH + 3O2 rarr 2CO2 + 3H2O 12 2777 1749 115 6298Hydrogen H2 + 12 O2 rarr H2O 2 286 2373 123 8297V2+ V2+ + VO2+ + 2H+

rarr V3+ + VO2+ + H2O 1 4318 4042 119 9361Methanol CH3OH + 12 O2 rarr CO2 + 2H2O 6 7266 7025 121 9668Formic acid HCOOH + 12 O2 rarr CO2 + 2H2O 2 2703 2855 148 1056

and easy to miniaturize [4] so that light and stackable fuelcells can be fabricated with simple microelectromechanicalsystems (MEMS) [5 6] The flexibility and the performanceimplications of operating membraneless sodium perboratefuel cell (MLSPBFC) under ldquoacid-alkaline mediardquo that is oneelectrode is acidic and the other one is alkaline condition willbe the focus of this study

Recent catalysis and fuel cell research has indicated thatformic acid may be a good alternative to the commonfuels of hydrogen and methanol [7 8] Even though formicacid has a lower energy density than methanol 749 and175 JmL respectively the possibility for a significant increasein performance with the correct catalyst exists [9] Comparedto hydrogen and methanol formic acid has a higher overalltheoretical open circuit potential and maximum efficiencyas indicated in Table 1 In sum formic acid seems to be apromising fuel for fuel cells and thus will be explored as thefuel with the membraneless fuel cell in this paper

However since the previous researchers used oxygensolution as the oxidant the performance of these micro fuelcells was found to be restricted severely by the low transportefficiency of oxygen in the cathode stream

In this communication for the first time we introducesodium perborate (NaBO

3

sdot 4H2

O) as an oxidant underldquoacid-alkaline mediardquo to demonstrate the performance ofa membraneless sodium perborate fuel cell (MLSPBFC)Sodium perborate is a true peroxo salt and is a convenientsource of hydrogen peroxide [10 11]

[B(OH)3

(O2

H)]minus +H2

O 999445999468 [B(OH)4

]minus

+H2

O2

(1)

The sodium perborate fuel cell (MLSPBFC) is uniquefrom previous fuel cells using H

2

O2

as mentioned in ourearlier study sodium perborate can be used not only as anoxidant but also as a reductant [12 13]

TheMLSPBFChas some advantages for example sodiumperborate is a cheap nontoxic and large scale industrialchemical which is used primarily in detergents and as a mildoxidant [14] The cell being more environmentally friendlythan the other fuel cells and the sodium perborate canbe handled more simply than hydrogen as it is a well-known fact that sodium perborate solution is a widespreadsafe disinfectant On the performance side the MLSPBFCgenerates electric power comparable to a typical air-breathingDMFC when operated in a microchemical channel at roomtemperature In addition the MLSPBFC requires no mem-brane electrode assemblies Thus the cost for the materials islow and the structure of the cell is simple

Table 2 Summary of the theoretical energy densities for differentfuels

Fuel Gravimetric energydensity (Wh kgminus1)

Volumetric energydensity (WhLminus1)

Formic acid 2086 1710Sodium borohydride 2925 2840Methanol 4690 6400Ethanol 6100 7850

Since formic acid fuel cells are capable of deliveringhigher energy densities than the most competitive recharge-able batteries [15] and can easily be obtained from fossilfuels such as natural gas or coal as well as from existencesources through fermentation of agricultural products andfrom biomasses we use formic acid as a fuel to study theperformance of MLSPBFC in this work This is an importantmetric in the development of converged electronic devicesas the operating time is becoming limited by conventionalbattery technology Table 2 provides relevant data aboutthe alternative fuels and their theoretical energy densitiesThese fuels exhibit higher volumetric and gravimetric energydensities than batteries Many works are under progress onthe development of microfluidic direct formic acid fuel cells[16ndash19]

Moreover in recent years the effect of operating lam-inar flow based fuel cells in all-acidic all-alkaline andacidicalkaline medium is highly focused [20 21] Sincecertain hydrocarbons such as formic acid and methanol caneasily be stored in liquid form under ambient conditionsare known to give safer high energy densities As for theacidalkaline bipolar electrolyte Ayato et al used a polymer-electrolyte membrane consisting of acid and alkaline ion-exchange layers for a HFC [22] The function of their bipolarmembrane wasmainly to keep the power stable bymodifyingwater management On the other hand we use the bipolarelectrolyte to force reactions (3) and (5) to proceed Thusthe use of perborate in the acidalkaline bipolar electrolyteis characteristic of the MLSPBFC

In this study a new branch of simplified architectures thatis unique from those that have been reported in the literaturehas been developed by eliminating and integrating the keycomponents of a conventional MEA With these advantagesmembraneless sodium perborate fuel cells (MLSPBFC) canbe used as an alternative for portable power applications


2 Experimental


3

sdot4H2


2

SO4


2

SO4





Cathode

Anode

Graphite

Oxidant

Fuel

Outlet

PMMA







0 2 4 6 8 10 12

02

00

04

06

08

10

All-acidic

Pote

ntia

l (V

)


(a)

0 2 4 6 8 10 12 14 16 18 20

All-alkaline

00

02

04

06

08

10

12

Pote

ntia

l (V

)


(b)


2

SO4


2

SO4





+ 2H+ + 2eminus 119864∘

= 022V (2)

Cathode

3H2

O2


O 119864∘

= 178V (3)


HCOOH + 3H2

O2


+ 6H2

O

119864∘

= 156V(4)



2minus

+ 4H2

O + 4eminus

119864∘

= minus117V(5)

Cathode

3H2

O2


= 0986V (6)


2HCOOminus + 3H2

O2


2minus

+ 4H2

O

119864∘

= 2156V(7)




SO4




+ 2H+ + 2eminus 119864∘

= 022V (8)

Cathode

H2

O2


= 0986V (9)


0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20


Pote

ntia

l (V

)

All-acidic



2

SO4


Overall

HCOOH + 3H2

O2

997888rarr CO2

+ 2H+ + 2OHminus

119864∘

= 0766V(10)





2minus

+ 2H2

O + 2eminus

119864∘

= minus117V(11)

Cathode

3H2

O2


O 119864∘

= 178V (12)

0

5

10

15

20

25

30


Pow

er d

ensit

y (m

W cm

minus2)



SO4


SO4


Overall

HCOOminus + 3H2

O2


2minus

+ 8H2

O

119864∘

= 295V(13)







00

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

20 M15 M10 M

05 M25 M

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)



SO4





00

02

04

06

08

10

12

14

16

18

20

0 10 20 30 40 50 60 700

5

10

15

20

25

30

Pote

ntia

l (V

)

0100 M0075 M0050 M

0025 M0010 M

Pow

er d

ensit

y (m

W cm

minus2)



SO4






000002004

006008

010

0

5

10

15

20

25

30

0001

0203

0405


0025 M0010 M

[Perborate]

Pow

er d

ensit

y (m

W cm

minus2

)

[H 2SO 4

]


2

SO4


2

SO4




SO4


2

SO4


2

SO4


SO4


2

SO4



0 20 40 60 80 1000

5

10

15

20

25

30

Pow

er d

ensit

y (m

W cm

minus2)



2

SO4




2

CO3


4 Conclusions



0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)

03 mL minminus1


min04 mL minus1

05 mL minminus1


08 mL minminus1



2

SO4

20 40 60 80 10012

14

16

18

20

Pote

ntia

l (V

)

62mA cmminus2

Time (100h)


SO4












Acknowledgment



References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


2 Experimental


3

sdot4H2


2

SO4


2

SO4





Cathode

Anode

Graphite

Oxidant

Fuel

Outlet

PMMA







0 2 4 6 8 10 12

02

00

04

06

08

10

All-acidic

Pote

ntia

l (V

)


(a)

0 2 4 6 8 10 12 14 16 18 20

All-alkaline

00

02

04

06

08

10

12

Pote

ntia

l (V

)


(b)


2

SO4


2

SO4





+ 2H+ + 2eminus 119864∘

= 022V (2)

Cathode

3H2

O2


O 119864∘

= 178V (3)


HCOOH + 3H2

O2


+ 6H2

O

119864∘

= 156V(4)



2minus

+ 4H2

O + 4eminus

119864∘

= minus117V(5)

Cathode

3H2

O2


= 0986V (6)


2HCOOminus + 3H2

O2


2minus

+ 4H2

O

119864∘

= 2156V(7)




SO4




+ 2H+ + 2eminus 119864∘

= 022V (8)

Cathode

H2

O2


= 0986V (9)


0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20


Pote

ntia

l (V

)

All-acidic



2

SO4


Overall

HCOOH + 3H2

O2

997888rarr CO2

+ 2H+ + 2OHminus

119864∘

= 0766V(10)





2minus

+ 2H2

O + 2eminus

119864∘

= minus117V(11)

Cathode

3H2

O2


O 119864∘

= 178V (12)

0

5

10

15

20

25

30


Pow

er d

ensit

y (m

W cm

minus2)



SO4


SO4


Overall

HCOOminus + 3H2

O2


2minus

+ 8H2

O

119864∘

= 295V(13)







00

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

20 M15 M10 M

05 M25 M

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)



SO4





00

02

04

06

08

10

12

14

16

18

20

0 10 20 30 40 50 60 700

5

10

15

20

25

30

Pote

ntia

l (V

)

0100 M0075 M0050 M

0025 M0010 M

Pow

er d

ensit

y (m

W cm

minus2)



SO4






000002004

006008

010

0

5

10

15

20

25

30

0001

0203

0405


0025 M0010 M

[Perborate]

Pow

er d

ensit

y (m

W cm

minus2

)

[H 2SO 4

]


2

SO4


2

SO4




SO4


2

SO4


2

SO4


SO4


2

SO4



0 20 40 60 80 1000

5

10

15

20

25

30

Pow

er d

ensit

y (m

W cm

minus2)



2

SO4




2

CO3


4 Conclusions



0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)

03 mL minminus1


min04 mL minus1

05 mL minminus1


08 mL minminus1



2

SO4

20 40 60 80 10012

14

16

18

20

Pote

ntia

l (V

)

62mA cmminus2

Time (100h)


SO4












Acknowledgment



References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 2 4 6 8 10 12

02

00

04

06

08

10

All-acidic

Pote

ntia

l (V

)


(a)

0 2 4 6 8 10 12 14 16 18 20

All-alkaline

00

02

04

06

08

10

12

Pote

ntia

l (V

)


(b)


2

SO4


2

SO4





+ 2H+ + 2eminus 119864∘

= 022V (2)

Cathode

3H2

O2


O 119864∘

= 178V (3)


HCOOH + 3H2

O2


+ 6H2

O

119864∘

= 156V(4)



2minus

+ 4H2

O + 4eminus

119864∘

= minus117V(5)

Cathode

3H2

O2


= 0986V (6)


2HCOOminus + 3H2

O2


2minus

+ 4H2

O

119864∘

= 2156V(7)




SO4




+ 2H+ + 2eminus 119864∘

= 022V (8)

Cathode

H2

O2


= 0986V (9)


0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20


Pote

ntia

l (V

)

All-acidic



2

SO4


Overall

HCOOH + 3H2

O2

997888rarr CO2

+ 2H+ + 2OHminus

119864∘

= 0766V(10)





2minus

+ 2H2

O + 2eminus

119864∘

= minus117V(11)

Cathode

3H2

O2


O 119864∘

= 178V (12)

0

5

10

15

20

25

30


Pow

er d

ensit

y (m

W cm

minus2)



SO4


SO4


Overall

HCOOminus + 3H2

O2


2minus

+ 8H2

O

119864∘

= 295V(13)







00

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

20 M15 M10 M

05 M25 M

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)



SO4





00

02

04

06

08

10

12

14

16

18

20

0 10 20 30 40 50 60 700

5

10

15

20

25

30

Pote

ntia

l (V

)

0100 M0075 M0050 M

0025 M0010 M

Pow

er d

ensit

y (m

W cm

minus2)



SO4






000002004

006008

010

0

5

10

15

20

25

30

0001

0203

0405


0025 M0010 M

[Perborate]

Pow

er d

ensit

y (m

W cm

minus2

)

[H 2SO 4

]


2

SO4


2

SO4




SO4


2

SO4


2

SO4


SO4


2

SO4



0 20 40 60 80 1000

5

10

15

20

25

30

Pow

er d

ensit

y (m

W cm

minus2)



2

SO4




2

CO3


4 Conclusions



0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)

03 mL minminus1


min04 mL minus1

05 mL minminus1


08 mL minminus1



2

SO4

20 40 60 80 10012

14

16

18

20

Pote

ntia

l (V

)

62mA cmminus2

Time (100h)


SO4












Acknowledgment



References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20


Pote

ntia

l (V

)

All-acidic



2

SO4


Overall

HCOOH + 3H2

O2

997888rarr CO2

+ 2H+ + 2OHminus

119864∘

= 0766V(10)





2minus

+ 2H2

O + 2eminus

119864∘

= minus117V(11)

Cathode

3H2

O2


O 119864∘

= 178V (12)

0

5

10

15

20

25

30


Pow

er d

ensit

y (m

W cm

minus2)



SO4


SO4


Overall

HCOOminus + 3H2

O2


2minus

+ 8H2

O

119864∘

= 295V(13)







00

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

20 M15 M10 M

05 M25 M

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)



SO4





00

02

04

06

08

10

12

14

16

18

20

0 10 20 30 40 50 60 700

5

10

15

20

25

30

Pote

ntia

l (V

)

0100 M0075 M0050 M

0025 M0010 M

Pow

er d

ensit

y (m

W cm

minus2)



SO4






000002004

006008

010

0

5

10

15

20

25

30

0001

0203

0405


0025 M0010 M

[Perborate]

Pow

er d

ensit

y (m

W cm

minus2

)

[H 2SO 4

]


2

SO4


2

SO4




SO4


2

SO4


2

SO4


SO4


2

SO4



0 20 40 60 80 1000

5

10

15

20

25

30

Pow

er d

ensit

y (m

W cm

minus2)



2

SO4




2

CO3


4 Conclusions



0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)

03 mL minminus1


min04 mL minus1

05 mL minminus1


08 mL minminus1



2

SO4

20 40 60 80 10012

14

16

18

20

Pote

ntia

l (V

)

62mA cmminus2

Time (100h)


SO4












Acknowledgment



References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




00

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

20 M15 M10 M

05 M25 M

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)



SO4





00

02

04

06

08

10

12

14

16

18

20

0 10 20 30 40 50 60 700

5

10

15

20

25

30

Pote

ntia

l (V

)

0100 M0075 M0050 M

0025 M0010 M

Pow

er d

ensit

y (m

W cm

minus2)



SO4






000002004

006008

010

0

5

10

15

20

25

30

0001

0203

0405


0025 M0010 M

[Perborate]

Pow

er d

ensit

y (m

W cm

minus2

)

[H 2SO 4

]


2

SO4


2

SO4




SO4


2

SO4


2

SO4


SO4


2

SO4



0 20 40 60 80 1000

5

10

15

20

25

30

Pow

er d

ensit

y (m

W cm

minus2)



2

SO4




2

CO3


4 Conclusions



0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)

03 mL minminus1


min04 mL minus1

05 mL minminus1


08 mL minminus1



2

SO4

20 40 60 80 10012

14

16

18

20

Pote

ntia

l (V

)

62mA cmminus2

Time (100h)


SO4












Acknowledgment



References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


000002004

006008

010

0

5

10

15

20

25

30

0001

0203

0405


0025 M0010 M

[Perborate]

Pow

er d

ensit

y (m

W cm

minus2

)

[H 2SO 4

]


2

SO4


2

SO4




SO4


2

SO4


2

SO4


SO4


2

SO4



0 20 40 60 80 1000

5

10

15

20

25

30

Pow

er d

ensit

y (m

W cm

minus2)



2

SO4




2

CO3


4 Conclusions



0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)

03 mL minminus1


min04 mL minus1

05 mL minminus1


08 mL minminus1



2

SO4

20 40 60 80 10012

14

16

18

20

Pote

ntia

l (V

)

62mA cmminus2

Time (100h)


SO4












Acknowledgment



References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 10 20 30 40 50 60 7000

02

04

06

08

10

12

14

16

18

20

0

5

10

15

20

25

30

Pote

ntia

l (V

)

Pow

er d

ensit

y (m

W cm

minus2)

03 mL minminus1


min04 mL minus1

05 mL minminus1


08 mL minminus1



2

SO4

20 40 60 80 10012

14

16

18

20

Pote

ntia

l (V

)

62mA cmminus2

Time (100h)


SO4












Acknowledgment



References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


References









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article development of membraneless sodium

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