An NMR study of methanol diffusion in polymer electrolyte fuel cell membranes

Every, Hayley A.; Hickner, Michael A.; McGrath, James E.; Zawodzinski, Thomas A.

doi:10.1016/j.memsci.2004.10.026

Cited by 67 publications

(46 citation statements)

References 18 publications

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“…As can be seen from the table, the permeability values obtained in the present work using the different techniques are comparable to each another. In addition, these values are in agreement with previously published results [13,15,21,24]. During the operation of a fuel cell, a water/methanol mixture reaches the cathode by electro-osmosis and the transfer increases with temperature.…”

Section: Potentiometric Techniquesupporting

confidence: 92%

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Comparative Study of Electrochemical Methods for Determination of Methanol Permeation Through Proton-Exchange Membranes

Zaidi

2011

Arab J Sci Eng

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In this work, methanol permeation rates were measured using various electrochemical techniques, namely, cyclic voltammetry, chronoamperometry and potentiometry. For all the methods, a Nafion ® 117 membrane was used to measure and evaluate methanol crossover rates. The purpose of this study is to compare the methanol permeation data obtained using the above-mentioned techniques under identical conditions, compare the data with the literature data, and then suggest the most accurate and reliable method for the determination of methanol crossover rates. The permeability values using these techniques were found to be in the range 1.11 × 10 −6 to 1.27 × 10 −6 cm 2 /s. The permeability values obtained using these techniques are close to one another and also compare well with the literature data for similar conditions; however, after careful screening of the data, it was found that the potentiometric technique is the easiest in terms of experimentation, reproducibility of results and accuracy, and gives more data points. This technique is suggested to be the best and most accurate for studying methanol permeation rates through membranes for direct methanol fuel cell applications.

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Section: Potentiometric Techniquesupporting

confidence: 92%

“…The partition coefficient between the membrane and the adjacent solution (K ) is dimensionless. Thus, in many studies of methanol permeation through polymer membranes, the units of diffusivity have been adopted for the membrane methanol-permeability [20][21][22][23][24]. …”

Section: Cyclic Voltammetry Techniquementioning

confidence: 99%

Comparative Study of Electrochemical Methods for Determination of Methanol Permeation Through Proton-Exchange Membranes

Zaidi

2011

Arab J Sci Eng

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“…Verbrugge [297] has reported the diffusion coefficient of methanol in Nafion 117 at 25 C using an electrodiffusion technique, and NMR has also been used for measuring the diffusion of methanol in Nafion 117 at 22 and 30 C [270,298]. Ren et al [299] have studied the methanol transport through Nafion membranes from 30 C to 130 C by resorting to a DMFC configuration method.…”

Section: Methanol Permeabilitymentioning

confidence: 99%

Membranes for Direct Alcohol Fuel Cells

Corti

2013

Direct Alcohol Fuel Cells

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This chapter is devoted to summarize and discuss the main properties of ionomeric membranes used in direct alcohol PEM fuel cells. Although Nafion is the proton exchange membrane commonly used in methanol and other direct alcohol fuel cells, other proton and alkaline membranes are being investigated in order to improve the efficiency of DAFC. The goals in the development of this critical component of DAFC are: low cost, long durability, low alcohol permeability and high electrical conductivity. The last two properties can be combined in a single parameter, the membrane selectivity that accounts for the ratio between the proton and alcohol transport through the membrane. This parameter can be compared to that measured for Nafion to define a relative selectivity, which is a primary parameter to evaluate the potentiality of a ionomer material to be used in alcohol feed fuel cells.The vast catalogue of polymeric materials reviewed here included Nafion composite with inorganic and organic fillers, and non-fluorinated proton conducting membranes such as sulfonated polyimides, poly(arylene ether)s, polysulfones, poly (vinyl alcohol), polystyrenes, and acid-doped polybenzimidazoles. Anionexchange membranes are also discussed because of the facile electro-oxidation of alcohols in alkaline media and because of the minimization of alcohol crossover in alkaline direct alcohol fuel cells.The performance of different types of membranes in direct alcohol fuel cells, mainly methanol, are summarized and discussed in order to identify the most promissory ones. The lack of correlation between the relative selectivity and fuel cell performance of the membranes indicates that the architecture of the three

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“…Based on the importance of the evaluation and understanding of the mass transport phenomena in PEMs, mutual diffusion coefficient of aqueous methanol solutions in Nafion 117, which is a perfluorosulfonate ionomer and commonly used as a PEM (Mauritz and Moore, 2004), have been measured by several techniques; the permeation method using a diffusion cell (Ve rburgge, 1989), the voltammetric method based on a electrochemical technique (Ren et al, 2000), and the time-resolved Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR) (Hallinan and Elabd, 2007). In addition, measurement of the self-diffusion coefficient in Nafion have been carried out by the nuclear magnetic resonance (NMR) spectroscopy (Hietala et al, 2000;Every et al, 2005). However, the different trend of the diffusion coefficient in Nafion on the methanol concentration was reported and we consider that there is no an established experimental technique.…”

Section: Introductionmentioning

confidence: 99%

Development of measurement technique of mass diffusion coefficient of aqueous methanol solutions in polymer electrolyte membranes based on infrared Soret forced Rayleigh scattering method using single crystal diamond window in a sample cell

Matsuura

Tokuda

Nagasaka

2018

JTST

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We have developed an experimental apparatus for the measurement of diffusion coefficient of aqueous methanol solutions in a polymer electrolyte membrane (PEM) for direct methanol fuel cells (DMFCs), based on the infrared Soret forced Rayleigh scattering (IR-SFRS) method. Because mass transport phenomena in PEMs play significant roles, evaluation and understanding of the mass diffusion in PEMs is important. In the present study, we developed a new sample cell using a single crystal diamond window, which transmits both the heating laser with the wavelength of 9.714 m and the probing laser with the wavelength of 639 nm. The heating wavelength was selected from the emission range of a valuable-wavelength carbon dioxide laser to utilize the absorption of methanol due to CO stretching. By using a single crystal diamond window, the scattered light of the probing laser generated at the window material which causes unpreferable effects on detection signals was reduced to about 1/150, compared to a polycrystalline diamond window. To evaluate the validity of the measurement system, we carried out experiments on the aqueous methanol solutions at a temperature of T = 298.2 K. The mass diffusion coefficient of the aqueous methanol solution with the mole fraction of 0.7 measured in the present study agreed with the measured values by the diaphragm cell technique within the relative standard uncertainty of 8.9%. After the validation, we performed experiments on three concentrations of aqueous methanol solutions in a PEM of Nafion 117 at T = 298.2 K. The mass diffusion in Nafion was observed in several hundreds of milliseconds. We obtained the mass diffusion coefficient with the relative standard uncertainties of 2.5-5.3%, depending on the methanol concentration. The mass diffusion coefficient in Nafion 117 was smaller than that of bulk aqueous methanol solutions, and increased with the increase in the methanol mole fraction.Keywords : Diffusion coefficient, Mass transport in membranes, Aqueous methanol solutions, Polymer electrolyte membrane (PEM), Nafion, Direct methanol fuel cell (DMFC), Optical measurement Matsuura, Tokuda and Nagasawa, Journal of Thermal Science and Technology, Vol.13, No.1 (2018)

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An NMR study of methanol diffusion in polymer electrolyte fuel cell membranes

Cited by 67 publications

References 18 publications

Comparative Study of Electrochemical Methods for Determination of Methanol Permeation Through Proton-Exchange Membranes

Comparative Study of Electrochemical Methods for Determination of Methanol Permeation Through Proton-Exchange Membranes

Membranes for Direct Alcohol Fuel Cells

Development of measurement technique of mass diffusion coefficient of aqueous methanol solutions in polymer electrolyte membranes based on infrared Soret forced Rayleigh scattering method using single crystal diamond window in a sample cell

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