This paper presents a study of the effects of an organic contaminant containing an amide bond (-CONH-), ε-caprolactam, on polymer electrolyte membrane fuel cells (PEMFCs). The ε-caprolactam has been detected in leachates from polyphthalamide materials that are being considered for use as balance-of-plant structural materials for PEMFCs. Contamination effects from ε-caprolactam in Nafion membranes are shown to be controlled by temperature. A possible explanation of the temperature effect is the endothermic ring-opening reaction of the amide bond (-NHCO-) of the cyclic ε-caprolactam. UV-vis and ATR-IR spectroscopy studies confirmed the presence of open ring structure of ε-caprolactam in membranes. The ECSA and kinetic current for the ORR of the Pt/C catalyst were also investigated and were observed to decrease upon contamination by the ε-caprolactam. By comparison of the CVs of ammonia and acetic acid, we confirmed the adsorption of carboxylic acid (-COOH) or carboxylate anion (-COO-) onto the surface of the Pt. Finally, a comparison of in situ voltage losses at 80 • C and 50 • C also revealed temperature effects, especially in the membrane, as a result of the dramatic increase in the HFR. Although research efforts have been made to reduce system costs and improve efficiency of polymer electrolyte membrane fuel cells (PEMFCs), cost and durability issues continue to delay their commercialization.1 In addition, because contamination of the stack can affect performance and durability, studies designed to elucidate these effects and mechanisms have been receiving more attention. 1-41In general, three fundamental contamination mechanisms are known: conductivity loss by ion exchange in the membrane/ionomer, Pt contamination by adsorption, and water/mass transport issues induced by changes in the gas diffusion layer (GDL) properties. Alkali, alkaline-earth, or transitional-metal cations such as Li + , Na + , K + , Cs + , Ni 2+ , Cu 2+ , Ca 2+ , and Fe 3+ are well known contaminants that undergo ion exchange [2][3][4][6][7][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] with the proton exchange membrane (PEM) in a PEMFC. Changes in the oxygen reduction reaction (ORR) kinetics at a Pt electrode covered with a Nafion ionomer [20][21][22][23][24] have also been reported. In addition to the decrease in PEM conductivity due to the reaction with cationic contaminants, a structural change also occurs in the ionomer. This structural change appears to be related to the degradation of Pt/C catalyst activity. Catalyst contamination by an adsorption mechanism from feed-gas contaminants such as SO 2 , [8][9] CO, 10 and H 2 S 11 are well known. In addition, we have reported that aniline adsorbs onto the Pt/C electrode because it contains an aromatic ring and a nitrogen atom in the form of an amine group. 31,35 In a recent cost analysis, 36,37 the need for cost reduction of balanceof-plant (BOP) materials increased relative to the need for cost reduction of the stack in PEMFCs. Using off-the-shelf materials ...

In this paper, we investigate contamination mechanisms and quantify the effect of organic model compounds aniline, diethyleneglycol monoethyl ether acetate, diethyleneglycol monoethyl ether, 4-methyl benzensulfonamide, benzyl alcohol, and 2,6-diaminotoluene that have been observed to originate from degradation of balance of plant materials on PEMFCs. In situ voltage loss can be quantified by contamination sources such as Pt, the ionomer, and the membrane using isotherm curves that are prepared by ex situ studies considering contamination mechanisms: adsorption on Pt, ion-exchange/absorption in membranes or electrodes. Severe kinetic loss of Pt activity on oxygen reduction reaction was observed for aromatic compounds due to the greater coverage on Pt/C than aliphatic compounds. An ion-exchange reaction by amine-containing aromatic compounds results in significant conductivity losses of the membrane/ionomer, which is main contributor of the performance loss in this study. That is, controlling the voltage losses caused by the membrane/ionomer contamination is critical to ensure the stability of the system. Infusion of non-amine containing compounds into PEMFCs also increased performance loss by an absorption mechanism but reached at steady state with reversible recovery by switching into normal operations without contaminants.

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