Durability test with fuel starvation using a Pt/CNF catalyst in PEMFC
© Jung et al; licensee Springer. 2012
Received: 9 September 2011
Accepted: 5 January 2012
Published: 5 January 2012
In this study, a catalyst was synthesized on carbon nanofibers [CNFs] with a herringbone-type morphology. The Pt/CNF catalyst exhibited low hydrophilicity, low surface area, high dispersion, and high graphitic behavior on physical analysis. Electrodes (5 cm2) were prepared by a spray method, and the durability of the Pt/CNF was evaluated by fuel starvation. The performance was compared with a commercial catalyst before and after accelerated tests. The fuel starvation caused carbon corrosion with a reverse voltage drop. The polarization curve, EIS, and cyclic voltammetry were analyzed in order to characterize the electrochemical properties of the Pt/CNF. The performance of a membrane electrode assembly fabricated from the Pt/CNF was maintained, and the electrochemical surface area and cell resistance showed the same trend. Therefore, CNFs are expected to be a good support in polymer electrolyte membrane fuel cells.
Keywordspolymer electrolyte membrane fuel cell catalyst carbon nanofiber durability
Each type of carbon has a different performance and durability, but carbon characteristics can also affect the corrosion rate [2, 18, 19]. Cell performance will decrease due to the increase in cell resistance with reduced thickness of the catalyst layer and electric contact of the current collector caused by carbon corrosion . Recently, graphitized carbon types, such as carbon nanofibers [CNFs], carbon nanotubes, and graphene, have been studied. Graphitic carbons are known to have high corrosion resistance as they have good thermal and electrochemical stability [19, 21–25]. CNFs have higher electric conductivity and durability than commercial CBs as catalyst support materials [19, 26]. However, it is difficult to synthesize platinum nanoparticles for loading and dispersion. CNFs with different structure and morphology have been used for electrode materials fabricated via various synthesis methods in order to achieve different surface chemistries [27–31]. CNFs are potentially suitable materials for high platinum loading and dispersion due to their many functional groups. The number of functional groups increases with increasing surface oxidation treatment time, producing a hydrophobic carbon surface which accelerates carbon corrosion .
In this study, we synthesized a catalyst with Pt particles of high loading and distribution on the CNFs. Membrane electrode assemblies [MEAs] were prepared using the Pt/CNF catalyst, and the performance changes caused by fuel starvation were evaluated via electrochemical analysis.
Synthesis of the Pt/CNF catalyst
The surface treatment and functionalization were carried out as follows. The CNFs (herringbone type) were placed in a flask, and H2SO4/HNO3 (v/v = 4:1) was added; the solution was ultrasonicated and stirred for 4 h. The CNFs were separated from the acids and washed with deionized water. A Pt salt precursor, H2PtCl6·6H2O (Sigma-Aldrich Corporation, St. Louis, MO, USA) was dissolved in ethylene glycol, and the CNF support was dispersed in the solution. The suspension was filtered and dried at 60°C for 4 h in a vacuum oven. The heat treatment was performed in argon atmosphere at 350°C for 2 h.
Manufacturing of the membrane electrode assembly
Catalysts used for the preparation of MEAs
A thermogravimetric analyzer [TGA] (Q50, TA Instruments, New Castle, DE, USA) was used to measure the amount of Pt loaded onto the carbon support. The crystal structure and particle size of the Pt were confirmed using an X-ray diffractometer [XRD] (RAD-3C, Rigaku Corporation, Tokyo, Japan with Cu-Kα (λ = 1.541 Å) at a scan rate of 1.5° min-1. The shape and dispersion of the Pt particles supported on the CNFs were verified by transmission electron microscopy [TEM] (JEM-2010, JEOL Ltd., Akishima, Tokyo, Japan) Brunauer-Emmett-Teller [BET] (ASAP2020, Micromeritics Instrument Co., Norcross, GA, USA) analysis was performed in order to measure the specific surface areas of the Pt/CNF and Pt/C catalysts.
The polarization curves of the unit cell were used to gauge the cell temperature at 70°C under atmospheric pressure using H2 and air at the anode and cathode, respectively. After obtaining the polarization curves, cyclic voltammetry [CV] was performed in the range of 0.05 to 1.2 V at a sweep rate of 50 mV/s with 20 and 100 cm3/min flow rates of H2 and N2 to the anode and cathode, respectively.
The durability of the assembled MEA was determined by acceleration tests using reverse potential operation under fuel starvation conditions. The acceleration experiment was operated at a current density of 400 mA/cm2. The hydrogen stoichiometry of the anode was maintained at 0.5. If the cell potential reached at -0.5 V, then the recovery system would be driven for 30 s under an open circuit voltage [OCV] state. In the OCV condition, the stoichiometric ratios of hydrogen and air were maintained at 1.5 and 2.0. This process was considered as 1 cycle, and experiments were repeated 200 times. After the acceleration tests, the performance curve and CV were obtained using the same method.
Results and discussion
Physical characteristics of the catalyst
Properties of Pt/CNF and Pt/C catalysts
Weight percentage by TGA (wt.%)
Surface area by BET (m2/g)
Dispersion of pore size (nm)
Pt particle size (nm)
Electrochemical measurement with fuel starvation
Summary of changes before and after the fuel starvation test
Performance at 0.6 V (mA/cm2)
Electrochemical surface area (m2/g)
Polarization resistance (Ω)
The 47.5 wt.% Pt/CNF catalyst was synthesized with a highly dispersed platinum. The Pt/CNF was used on the anode and on both electrodes. The MEAs were evaluated for durability against fuel starvation. After 200 cycles of reverse voltage drops, the performance of MEA-1 with Pt/C using both electrodes decreased by 59%, whereas the performance of the MEA-2 and MEA-3 was maintained. In the CV and EIS analyses, the ESA and cell resistance of the MEAs with Pt/CNF were nearly unchanged. As a result, a catalyst on a CNF support which has higher graphitization, lower specific surface area, and lower hydrophilicity has higher carbon corrosion resistance than a commercial Pt/C catalyst.
electrochemical surface area
membrane electrode assembly
open circuit viltage
polymer electrolyte membrane fuel cell
transmission electron microscopy
- Lee DY, Hwang SW: Effect of loading and distributions of Nafion ionomer in the catalyst layer for PEMFCs. Int J Hydrogen Energy 2009, 33: 2790–2794.View ArticleGoogle Scholar
- Yu X, Ye S: Recent advances in activity and durability enhancement of Pt/C catalytic cathode in PEMFC: part II: degradation mechanism and durability enhancement of carbon supported platinum catalyst. J Power Sources 2007, 172: 145–154. 10.1016/j.jpowsour.2007.07.048View ArticleGoogle Scholar
- Knights SD, Colbow KM, St-Pierre J, Wilkinson DP: Aging mechanisms and lifetime of PEFC and DMFC. J Power Sources 2004, 127: 127–134. 10.1016/j.jpowsour.2003.09.033View ArticleGoogle Scholar
- Stevens DA, Dahn JR: Thermal degradation of the support in carbon-supported platinum electrocatalysts for PEM fuel cells. Carbon 2005, 43: 179–188. 10.1016/j.carbon.2004.09.004View ArticleGoogle Scholar
- Antolini E: Formation, microstructural characteristics and stability of carbon supported platinum catalysts for low temperature fuel cells. J Mater Sci 2003, 38: 2995–3005. 10.1023/A:1024771618027View ArticleGoogle Scholar
- Cheng X, Chen L, Peng C, Chen ZW, Zhang Y, Fan QB: Catalyst microstructure examination of PEMFC membrane electrode assemblies vs. time. J Electrochem Soc 2004, 151: A48-A52. 10.1149/1.1625944View ArticleGoogle Scholar
- Willsau J, Heitbaum J: The influence of Pt-activation on the corrosion of carbon in gas diffusion electrodes--a dems study. J Electroanal Chem 1984, 161: 93–101. 10.1016/S0022-0728(84)80252-1View ArticleGoogle Scholar
- Dicks Al: The role of carbon in fuel cells. J Power Sources 2006, 156: 128–141. 10.1016/j.jpowsour.2006.02.054View ArticleGoogle Scholar
- Shao Y, Wang J, Kou R, Engelhard M, Li J, Wang Y, Lin Y: The corrosion of PEM fuel cell catalyst supports and its implications for developing durable catalysts. Electrochim Acta 2009, 54: 3109–3114. 10.1016/j.electacta.2008.12.001View ArticleGoogle Scholar
- Shao Y, Yin G, Gao Y: Understanding and approaches for the durability issues of Pt-based catalysts for PEM fuel cell. J Power Sources 2007, 171: 558–566. 10.1016/j.jpowsour.2007.07.004View ArticleGoogle Scholar
- Wang X, Li W, Chen Z, Waje M, Yan Y: Durability investigation of carbon nanotube as catalyst support for proton exchange membrane fuel cell. J Power Sources 2006, 158: 154–159. 10.1016/j.jpowsour.2005.09.039View ArticleGoogle Scholar
- Taniguchi A, Akita T, Yasuda K, Miyazaki Y: Analysis of electrocatalyst degradation in PEMFC caused by cell reversal during fuel starvation. J Power Sources 2004, 130: 42–49. 10.1016/j.jpowsour.2003.12.035View ArticleGoogle Scholar
- Reiser CA, Bregoli L, Patterson TW, Yi JS, Yang JD, Perry ML, Jarvi TD: A reverse-current decay mechanism for fuel cells. Electrochem Solid State Lett 2005, 8: A273-A276. 10.1149/1.1896466View ArticleGoogle Scholar
- Tang H, Qi Z, Ramani M, Elter JF: PEM fuel cell cathode carbon corrosion due to the formation of air/fuel boundary at the anode. J Power Sources 2006, 158: 1306–1312. 10.1016/j.jpowsour.2005.10.059View ArticleGoogle Scholar
- Wang Y: Analysis of the key parameters in the cold start of polymer electrolyte fuel cells. J Electrochem Soc 2007, 154: B1041-B1048. 10.1149/1.2767849View ArticleGoogle Scholar
- Ralph TR, Hudson S, Wilkinson DP: Electrocatalyst stability in PEMFCs and the role of fuel starvation and cell reversal tolerant anodes. ECS Trans 2006, 1: 67–84.View ArticleGoogle Scholar
- Kang JT, Jung DW, Park S, Lee JH, Ko JJ, Kim JB: Accelerated test analysis of reversal potential caused by fuel starvation during PEMFCs operation. Int J Hydrogen Energy 2010, 35: 3727–3735. 10.1016/j.ijhydene.2010.01.071View ArticleGoogle Scholar
- Yu X, Ye S: Recent advances in activity and durability enhancement of Pt/C catalytic cathode in PEMFC: part I. Physico-chemical and electronic interaction between Pt and carbon support, and activity enhancement of Pt/C catalyst. J Power Sources 2007, 172: 133–144. 10.1016/j.jpowsour.2007.07.049View ArticleGoogle Scholar
- Serp P, Corrias M, Kalck P: Carbon nanotubes and nanofibers in catalysis. Appl Catal A 2003, 253: 337–358. 10.1016/S0926-860X(03)00549-0View ArticleGoogle Scholar
- Guilminot E, Corcella A, Charlot F, Maillard F, Chatenet M: Detection of Pt z+ ions and Pt nanoparticles inside the membrane of a used PEMFC. J Electrochem Soc 2007, 154: B96-B105. 10.1149/1.2388863View ArticleGoogle Scholar
- Bessel CA, Laubernds K, Rodriguez NM, Baker RTK: Graphite nanofibers as an electrode for fuel cell applications. J Phys Chem B 2001, 105: 1115–1118. 10.1021/jp003280dView ArticleGoogle Scholar
- Wang J, Yin G, Shao Y, Wang Z, Gao Y: Electrochemical durability investigation of single-walled and multi-walled carbon nanotubes under potentiostatic conditions. J Power Sources 2008, 176: 128–131. 10.1016/j.jpowsour.2007.10.057View ArticleGoogle Scholar
- Shao Y, Yin G, Zhang J, Gao Y: Comparative investigation of the resistance to electrochemical oxidation of carbon black and carbon nanotubes in aqueous sulfuric acid solution. Electrochim Acta 2006, 51: 5853–5857. 10.1016/j.electacta.2006.03.021View ArticleGoogle Scholar
- Saminathan K, Kamavaram V, Veedu V, Kannan AM: Preparation and evaluation of electrodeposited platinum nanoparticles on in situ carbon nanotubes grown carbon paper for proton exchange membrane fuel cells. Int J Hydrogen Energy 2009, 34: 3838–3844. 10.1016/j.ijhydene.2009.03.009View ArticleGoogle Scholar
- Stevens DA, Hicks MT, Haugen GM, Dahn JR: Ex situ and in situ stability studies of PEMFC catalysts. J Electrochem Soc 2005, 152: A2309-A2315. 10.1149/1.2097361View ArticleGoogle Scholar
- Endo M, Kim YA, Hayashi T, Nishimura K, Matusita T, Miyashita K, Dresselhaus MS: Structural characterization of carbon nanofibers obtained by hydrocarbon pyrolysis. Carbon 2001, 39: 2003–2010. 10.1016/S0008-6223(01)00019-7View ArticleGoogle Scholar
- Ismagilov ZR, Kerzhentsev MA, Shikina NV, Lisitsyn AS, Okhlopkova LB, Barnakov ChN, Sakashita M, Iijima T, Tadokoro K: Development of active catalysts for low Pt loading cathodes of PEMFC by surface tailoring of nanocarbon materials. Catalysis Today 2005, 102–103: 58–66.View ArticleGoogle Scholar
- Wallnöfer E, Perchthaler M, Hacker V, Squadrito G: Optimisation of carbon nanofiber based electrodes for polymer electrolyte membrane fuel cells prepared by a sedimentation method. J Power Sources 2009, 188: 192–198. 10.1016/j.jpowsour.2008.11.052View ArticleGoogle Scholar
- Alcaide F, Álvarez G, Miguel O, Lázaro MJ, Moliner R, Cudero AL, Gullón JS, Herrero E, Aldaz A: Pt supported on carbon nanofibers as electrocatalyst for low temperature polymer electrolyte membrane fuel cells. Electrochem Commun 2009, 11: 1081–1084. 10.1016/j.elecom.2009.03.023View ArticleGoogle Scholar
- Yuan F, Yu HK, Ryu H: Preparation and characterization of carbon nanofibers as catalyst support material for PEMFC. Electrochimica Acta 2004, 50: 685–691. 10.1016/j.electacta.2004.01.106View ArticleGoogle Scholar
- Calvillo L, Gangeri M, Perathoner S, Centi G, Moliner R, Lázaro MJ: Effect of the support properties on the preparation and performance of platinum catalysts supported on carbon nanofibers. J Power Sources 2009, 192: 144–150. 10.1016/j.jpowsour.2009.01.005View ArticleGoogle Scholar
- Oh HS, Kim KH, Ko YJ, Kim HS: Effect of chemical oxidation of CNFs on the electrochemical carbon corrosion in polymer electrolyte membrane fuel cells. Int J Hydrogen Energy 2011, 35: 701–708.View ArticleGoogle Scholar
- Kong CS, Kim DY, Lee HK, Shul YG, Lee TH: Influence of pore-size distribution of diffusion layer on mass-transport problems of proton exchange membrane fuel cells. J Power Sources 2002, 108: 185–191. 10.1016/S0378-7753(02)00028-9View ArticleGoogle Scholar
- Mu S, Xu C, Gao Y, Tang H, Pan M: Accelerated durability tests of catalyst layers with various pore volume for catalyst coated membranes applied in PEM fuel cells. Int J Hydrogen Energy 2008, 35: 2872–2876.View ArticleGoogle Scholar
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