Fuel Cells - Fundamentals and Applications

Carrette, Linda; Friedrich, K. Andreas; Stimming, Ulrich

doi:10.1002/1615-6854(200105)1:1<5::aid-fuce5>3.0.co;2-g

Cited by 1,445 publications

(952 citation statements)

References 138 publications

Supporting

Mentioning

930

Contrasting

Unclassified

Order By: Relevance

“…At present, various sulfonated perfluropolymers such as Nafion, Flemion, and Aciplex have been perceived as the highest proton conductive membranes in their fully hydrated states because they exhibit high proton conductivities and excellent chemical and mechanical stabilities. However, these commercial membranes have several drawbacks including high cost, high methanol crossover, and loss of proton conductivity at temperatures above 80 °C, which limit their application in DMFC 2 . Alternatively, J.…”

Section: Introductionmentioning

confidence: 99%

Proton Exchange Membrane Based on Sulfonated Poly (Aromatic Imide-Co-Aliphatic Imide) for Direct Methanol Fuel Cell

et al. 2017

View full text Add to dashboard Cite

A new sulfonated poly(aromatic imide-co-aliphatic imide) (SPI) for the use as a polymer electrolyte membrane was successfully synthesized from 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenylmethane-2,2'-disulfonic acid disodium salt (S-DDM), hexamethylenediamine, and 3,3',4,4'-benzophenonetetracarboxylic dianhydride in a one-step reaction. S-DDM was prepared by the direct sulfonation of DDM monomer. The degree of sulfonation of the sulfonated copolyimide was varied by using various molar concentrations of S-DDM. The sulfonated copolyimide with the highest degree of sulfonation possessed the proton conductivity of 0.0032 S.cm -1 in a wet state. The highest methanol permeability of the sulfonated copolyimide was 2.75 × 10 -8 cm 2 .s -1 which is ~425 times lower than that of the Nafion 117. The highest membrane selectivity belonged to the membrane with 34% degree of sulfonation with the value of 1.65 × 10 6 s.S.cm -3 which is three orders of magnitude higher than the commercial Nafion 117.

show abstract

Section: Introductionmentioning

confidence: 99%

Proton Exchange Membrane Based on Sulfonated Poly (Aromatic Imide-Co-Aliphatic Imide) for Direct Methanol Fuel Cell

et al. 2017

View full text Add to dashboard Cite

show abstract

“…[1][2][3] Perfluorosulfonic acid (PFSA) polymers such as Nafion (DuPont) are the most promising and state-of-the-art polymer electrolyte membranes (PEM) for PEMFC. However, the material has several shortcomings that limit its utility and performance, such as reduced proton conductivity at elevated temperatures (>80°C), high methanol/gas diffusion, environmental incompatibility (poor recyclability), and significant manufacturing costs.…”

Section: Introductionmentioning

confidence: 99%

Polymer Electrolyte Membranes Derived from New Sulfone Monomers with Pendent Sulfonic Acid Groups

et al. 2010

View full text Add to dashboard Cite

New monomers containing two or four pendent phenyl groups were synthesized by bromination of bis(4-fluorophenyl) sulfone, followed by Suzuki coupling with benzeneboronic acid. The resulting monomers were converted to the corresponding sulfonated monomers having two or four pendent sulfonic acid groups, predominately at the p-phenyl position. Aromatic nucleophilic substitution (SNAr) polycondensation using the di- and tetrasulfonated monomers provided sulfonated poly(arylene ether sulfone) copolymers S2-PAES-xx and S4-PAES-xx, respectively, where xx refers to the molar ratio of the sulfonated to non-sulfonated pendent phenyl monomer. Copoly(arylene ether sulfone)s based on the corresponding non-sulfonated monomers were also synthesized for a parallel study on postpolymerization sulfonation of these copolymers. Postsulfonation occurred predominately at the para-pendent phenyl site, and the reactions were complete within a short time (about 30 min), without evidence of chain degradation. Flexible and tough membranes having high mechanical strength were obtained by solution casting of all four series of copolymers. The copolymers with two or four pendent sulfonic acid groups had high proton conductivities in the range of 44−142 mS/cm for S2-PAES-xx and 51−158 mS/cm for S4-PAES-xx at room temperature, respectively. The methanol permeabilities of these copolymers were in the range of 0.8 × 10−8−15.0 × 10−7 cm2/s, which is lower than Nafion (16.7 × 10−7 cm2/s). The S4-PAES-xx membranes displayed better properties (lower water uptake and higher proton conductivities) than the S2-PAES-xx membranes, which can be attributed to the more blocky architecture of the sulfonic acid groups in the S4 membranes. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for some of the obtained copolymers indicated that they are good candidate materials for proton exchange membrane in fuel cell applications.

show abstract

“…[1][2][3] Limitations associated to the high overpotential and the existence of parallel reaction pathways makes its understanding a rather challenging task. Studies have been carried out mainly on platinum surfaces, both polycrystalline and single crystals, by means of different electrochemical approaches sometimes coupled to other in situ and on line techniques.…”

Section: Introductionmentioning

confidence: 99%

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Martins¹,

Batista²,

Sitta³

et al. 2008

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

Descreve-se neste artigo a observação experimental de dinâmica oscilatória durante a oxidação eletrocatalítica de metanol sobre platina. Além das, previamente relatadas, oscilações de potencial, oscilações de corrente obtidas sob controle potenciostático também são apresentadas. A região de existência de oscilações de corrente é mapeada no plano de bifurcação voltagem aplicada x resistência. Conjuntamente com investigações eletroquímicas, espectroscopia FTIR in situ também foi aplicada nestes estudos. Apesar de não ter sido possível acompanhar eventuais variações de intermediários reacionais durante as oscilações, tais experimentos revelaram que a cobertura média de monóxido de carbono permanece consideravelmente alta durante as oscilações. Os resultados são discutidos e comparados com as oscilações observadas na eletrooxidação de ácido fórmico, um sistema cujo comportamento é mais entendido e amplamente fundamentado por dados espectroscópicos obtidos in situ.It is described in this paper the experimental observation of oscillatory dynamics during the electrocatalytic oxidation of methanol on platinum. Besides the previously reported potential oscillations, current oscillations obtained under potentiostatic control are also presented. The existence region of current oscillations is mapped in an applied voltage x resistance bifurcation diagram. Conjointly with electrochemical investigations, in situ FTIR spectroscopy was also employed in the present studies. Although we were not able to follow eventual intermediate coverage changes during the oscillations, those experiments revealled that the mean coverage of adsorbed carbon monoxide remains appreciably high along the oscillations. Results are discussed and compared with the oscillations observed in the electrooxidation of formic acid, a system whose behavior is more understood and widely supported by in situ spectroscopic data. Keywords: current and potential oscillations, methanol, electrocatalysis, in situ FTIR IntroductionMethanol has been pointed as one of the most promising organic molecules to be used in large scale energy conversion systems, as in the so-called direct methanol fuel cells (DMFC). [1][2][3] Limitations associated to the high overpotential and the existence of parallel reaction pathways makes its understanding a rather challenging task. Studies have been carried out mainly on platinum surfaces, both polycrystalline and single crystals, by means of different electrochemical approaches sometimes coupled to other in situ and on line techniques. [4][5][6][7][8][9][10][11][12][13][14][15][16] In most of these reports, the focus stands on the electrocatalytic aspects of the methanol oxidation and encompasses questions such as the relationship between reaction rate and applied potential, the impact of the interfacial structure on reaction rate and selectivity, and the nature and geometry of adsorbates, to list a few. By far less studied however are the issues related to the complex kinetic aspects associated to the electrooxidation of methanol.In o...

show abstract

Fuel Cells - Fundamentals and Applications

Cited by 1,445 publications

References 138 publications

Proton Exchange Membrane Based on Sulfonated Poly (Aromatic Imide-Co-Aliphatic Imide) for Direct Methanol Fuel Cell

Proton Exchange Membrane Based on Sulfonated Poly (Aromatic Imide-Co-Aliphatic Imide) for Direct Methanol Fuel Cell

Polymer Electrolyte Membranes Derived from New Sulfone Monomers with Pendent Sulfonic Acid Groups

Oscillatory instabilities during the electrocatalytic oxidation of methanol on platinum

Contact Info

Product

Resources

About