Electrochimica Acta 56 (2011) 9467–9475 Contents lists available at ScienceDirect Electrochimica Acta jou rn al hom epa ge: www.elsevier.com/locate/electacta The influence of CO on the current density distribution of high temperature polymer electrolyte membrane fuel cells M. Boaventura a , H. Sander b , K.A. Friedrich b , A. Mendes a,∗ a Laboratório de Engenharia de Processos, Ambiente e Energia (LEPAE), Faculdade de Engenharia da Universidade do Porto, Rua Roberto Frias s/n, 4200-465 Porto, Portugal b Institut für Technische Thermodynamik, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Pfaffenwaldring 38-40, D-70569 Stuttgart, Germany a r t i c l e i n f o Article history: Received 5 January 2011 Received in revised form 12 August 2011 Accepted 12 August 2011 Available online 19 August 2011 Keywords: Carbon monoxide in hydrogen Fuel cell Segmented cell Current distribution a b s t r a c t In this work the poisoning effect of carbon monoxide (CO) on the performance of high temperature poly- mer electrolyte membrane (PEM) fuel cell is reported. The poisoning of the anode is assessed at 160 ◦ C and 180 ◦ C based on the transient behavior of the fuel cell potential and current density distribution. The current density distribution at similar cell potential and global current density is also critically com- pared for CO-free hydrogen feed and for CO-contaminated hydrogen feed. Furthermore, the current–cell potential (I–V) and power density curves and impedance spectra are obtained. The presence of CO causes a performance loss which is aggravated for higher CO concentrations and higher current densities and for lower temperatures. The transient behavior of the fuel cell potential and current density distribution show that the poisoning effect of carbon monoxide at the anode is very fast. The use of CO contaminated hydrogen at the anode yields an anisotropic distribution of carbon monox- ide, which is accentuated for higher carbon monoxide concentrations and current densities. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Polymer electrolyte membrane fuel cell (PEMFC) is a clean technology that has been considered for stationary applications and as an alternative to internal combustion engines. The most used and effective catalyst for the oxidation of pure hydrogen is platinum. When pure hydrogen is feed to the anode and air/oxygen to the cathode, high power densities of the fuel cell are achieved without any emissions beside water vapor. Since hydrogen production from renewable sources is still under development, it is expected in the near future that low cost hydrogen is generated by steam reforming of natural gas, by partial oxidation of hydrocarbons or by gasification of coal. Hydrogen produced by these processes contains usually 1–2% of CO [1–3]. An on-board production of hydrogen is often considered due to hydrogen storage constrains and lack of refueling infrastruc- tures. At typical fuel cell operating temperature (below 90 ◦ C), a decrease in the catalyst activity is observed when small amounts of carbon monoxide (CO), such as 10 ppm, is introduced into the hydrogen feed. The poisoning effect of CO can be mitigated by (i) advanced purification of the reformate gas, (ii) introduction of an oxidant bleed at the anode feed or (iii) use of a more CO tolerant ∗ Corresponding author. Tel.: +351 225081695; fax: +351 225081449. E-mail address: mendes@fe.up.pt (A. Mendes). catalyst [1,4,5]. The first approach increases the system complex- ity and cost whereas the second compromises safety [3,6–8]. The development of new electrocatalysts has been focused on bimetal- lic catalysts (like PtRu/C and PtSn/C), but the effectiveness and durability is still an issue [8]. The carbon monoxide strongly adsorbs on platinum surface, reducing the activity of the catalyst. The adsorption of CO is associated with a negative entropy change and therefore dis- favored at higher temperatures [6,8–10]. The behavior of high temperature PEMFC (100–200 ◦ C) is assessed by some authors that performed experiments with hydrogen containing different con- centrations of CO [9,11–15]. Higher temperatures lead to lower performance degradation in the presence of CO when compared to the lower operation temperatures. Good tolerance of a Pt/C cat- alyst is observed with 3% of CO at 200 ◦ C up to 1.0 A cm -2 or cell potential above 0.50 V [9], and with 3% and 5% of CO at 180 ◦ C, at moderate values of potential [11]. It is also shown that the perfor- mance of the fuel cell operating at 210 ◦ C is not affected by 1.0% of CO in the anode feed [12]. These studies demonstrate that the increase of the fuel cell temperature is an alternative to diminish the contamination of the anode catalyst, showing the viability of direct use of reformate gas on the fuel cell anode and the possi- bility of successful incorporation of reformers in high temperature PEMFC systems. Pan et al. integrated a high temperature PEMFC with a methanol reformer [16]. The CO amount at the reformate gas is below 0.2% and at temperatures between 135 ◦ C and 170 ◦ C only a slightly decrease in performance is observed in a single fuel cell. 0013-4686/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.electacta.2011.08.039