An investigation of the oxygen reduction reaction (ORR) on carbon-supported Pt catalysts used as fuel cell electrodes in phosphoric acid-imbibed polybenzimidazole (PBI) is reported. Electrodes of different thickness were investigated by employing catalysts with different loadings of Pt on carbon and different amounts of PBI. The electrochemical surface areas (ESAs) of the catalyst were measured using cyclic voltammetry. ESAs decreased with an increase in Pt loading on the catalyst but were not significantly affected by changes in acid content in the catalyst electrodes. The influence of phosphoric acid and temperature on ORR was determined using linear sweep voltammetry. High levels of phosphoric acid (16 per repeat polymer unit (PRU)) in the cathode catalyst layer were detrimental to ORR performance. Good oxygen reduction performance was obtained with a 40 per cent Pt/C catalyst incorporating phosphoric acid at a level of 3 PRU. Kinetic parameters (transfer coefficient, exchange current density, and oxygen reaction order) were determined.
DamjanovicA.BrusicV., ‘Electrode kinetics of oxygen reduction on oxide-free platinum electrodes’Electrochim. Acta12 (6) (1967): 615–628.
2.
DamjanovicA.SepaD. B.VojnovicM. V., ‘New evidence supports the proposed mechanism for O2 reduction at oxide free platinum electrodes’Electrochim. Acta24 (8) (1979): 887–889.
3.
BagotzkyV. S.TarasevichM. R., ‘Oxygen adsorption on platinum and platinum metals. Part I: investigation of the adsorption mechanism by the potentiodynamic method’J. Electroanal. Chem. Interfacial Electrochem.101 (1) (1979): 1–17.
4.
MullerL.MansurovG. N.PetriiO. A., ‘The measurment of strong adsorption on platinum film electrodes by surface conductance’J. Electroanal. Chem.96 (1971): 159–164.
5.
SunW.PeppleyB. A.KaranK., ‘An improved two-dimensional agglomerate cathode model to study the influence of catalyst layer structural parameters’Electrochim. Acta50 (16–17) (2005): 3359–3374.
6.
ApplebyA. J., ‘Oxygen reduction on oxide-free platinum in 85% orthophosphoric acid: temperature and impurity dependence’J. Electrochem. Soc.117 (3) (1970): 328–335.
7.
ConwayB. E.TessierD. F.WilkinsonD. P., ‘Experimental evidence for the potential-dependence of entropy of activation in electrochemical reactions in relations to the temperature-dependence of Tafel slopes’J. Electroanal. Chem.199 (2) (1986): 249–269.
8.
ParthasarathyA.SrinivasanS.ApplebyA. J., ‘Temperature dependence of the electrode kinetics of oxygen reduction at the platinum/Nafion® interface — a microelectrode investigation’J. Electrochem. Soc.139 (9) (1992): 2530–2537.
9.
ApplebyA. J.BakerB. S., ‘Oxygen reduction on platinum in trifluoromethane sulfonic acid’J. Electrochem. Soc.125 (3) (1978): 404–406.
10.
VogelW. M.LundquistJ. T., ‘Reduction of oxygen on Teflon-bonded platinum electrodes’J. Electrochem. Soc.117 (12) (1970): 1512–1516.
11.
ClouserS. J.HuangJ. C.YeagerE., ‘Temperature dependence of the Tafel slope for oxygen reduction on platinum in concentrated phosphoric acid’J. Appl. Electrochem.23 (1991): 597–605.
12.
McBreenJ.O'GradyW. E.RichterR., ‘A rotating disk electrode apparatus for the study of fuel cell reactions at elevated temperatures and pressures’J. Electrochem. Soc.131 (5) (1984): 1215–1216.
13.
ApplebyA. J., ‘Evolution and reduction of oxygen on oxidized platinum in 85% orthophosphoric acid’J. Electroanal. Chem. Interfacial Electrochem.24 (1971): 97.
14.
O'GradyW. E.TaylorE. J.SrinivasanS., ‘Electro-reduction of oxygen on reduced platinum in 85% phosphoric acid’J. Electroanal. Chem. Interfacial Electrochem.132 (1981): 137.
15.
HuangJ. C.SenR. K.YeagerE., ‘Oxygen reduction on platinum in 85% orthophosphoric acid’J. Electrochem. Soc.126 (5) (1979): 786–792.
16.
KunzH. R.GruverG. A., ‘The catalytic activity of platinum supported on carbon for electrochemical oxygen reduction in phosphoric acid’J. Electrochem. Soc.122 (10) (1975): 1279–1287.
17.
ScharifkerB. R.ZelenayP.BockrisJ. O. M., ‘The kinetics of oxygen reduction in molten phosphoric acid at high temperatures’J. Electrochem. Soc.134 (1981): 2714–2725.
18.
WangJ.-T.SavinellR. F.WainrightJ.LittM.YuH., ‘A H-2/O-2 fuel cell using acid doped polybenzimidazole as polymer electrolyte’Electrochim. Acta41 (2) (1996): 193–197.
19.
PanC.LiQ.JensenJ. O.HeR.MortenL. N. CleemanNilssonS.BjerrumN. J.ZengQ., ‘Preparation and operation of gas diffusion electrodes for high-temperature proton exchange membrane fuel cells’J. Power Sources172 (2002): 278–286.
20.
SelandF.BerningT.BørresenandB.TunoldR., ‘Improving the performance of high-temperature PEM fuel cells based on PBI electrolyte’J. Power Sources160 (1) (2006): 27–36.
LobatoJ.RodrigoM. A.LinaresJ. J.ScottK., ‘Effect of the catalytic ink preparation method on the performance of high temperature polymer electrolyte membrane fuel cells’J. Power Sources157 (1) (2006): 284–292.
23.
KongsteinO. E.BerningT.BørresenB.SelandF.TunoldR., ‘Polymer electrolyte fuel cells based on phosphoric acid doped polybenzimidazole (PBI) membranes’Energy32 (4) (2007): 418–422.
24.
LiuZ.WainrightJ. S.LittM. H.SavinellR. F., ‘Study of the oxygen reduction reaction (ORR) at Pt interfaced with phosphoric acid doped polybenzimidazole at elevated temperature and low relative humidity’Electrochim. Acta51 (19) (2006): 3914–3923.
25.
LobatoJ.CañizaresP.RodrigoM. A.LinaresJ. J.PinarF. J., ‘Study of the influence of the amount of PBI—H3PO4 in the catalytic layer of a high temperature PEMFC’Int. J. Hydrog. Energy35 (3) (2010): 1347–1355.
26.
WangY.FengX. J., ‘Analysis of reaction rates in the cathode electrode of polymer electrolyte fuel cell I. Single-layer electrodes’Electrochem. Soc.155 (12) (2008): B1289–B1295.
27.
KordeschK.SimaderG., Fuel cells and their applications (UK: Wiley-VCH, Cambridge1996).
LufranoF.StaitiP., ‘Conductivity and capacitance properties of a supercapacitor based on Nafion electrolyte in a nonaqueous system’Electrochem. Solid-State Lett.711 (2004): A447–A450.
30.
SugishimaN.HinatsuJ. T.FoulkesF. R., ‘Phosphorous acid impurities in phosphoric acid fuel cell electrolytes. II. Effects on the oxygen reduction reaction at platinum electrodes’J. Electrochem. Soc.141 (12) (1994): 332–335.
31.
LiQ. F.HjulerH. A.BjerrumN. J., ‘Oxygen reduction on carbon supported platinum catalysts in high temperature polymer electrolytes’Electrochim. Acta45 (25–26) (2000): 4219–4226.
32.
BeversD.WohrM.YasudaK.OguroK., ‘Simulation of a polymer electrolyte fuel cell electrode’J. Appl. Electrochem.27 (1991): 1254–1264.
33.
LiuZ. Y.WainrightJ. S.SavinellR. F., ‘High-temperature polymer electrolytes for PEM fuel cells: study of the oxygen reduction reaction (ORR) at a Pt-polymer electrolyte interface’Chem. Eng. Sci.59 (22–23) (2004): 4833–4838.
34.
BockrisJ. O. M.ConwayB. E. Eds., Modern aspects of electrochemistry (London: Butterworth Scientific Publications1954).
