Surface-modified carbons as platinum catalyst support for PEM fuel cells

Guha, Abhishek; Lü, Weijie; Zawodzinski, Thomas A.; Schiraldi, David A.

doi:10.1016/j.carbon.2007.03.023

Cited by 189 publications

(119 citation statements)

References 35 publications

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“…[15]. The reactivity of a covalent bond to hydrogen with respect to abstraction by hydroxyl radical can be readily inferred from the strength of the bond to hydrogen as shown by the strong correlation between experimental bond strengths and rates of abstraction given in Figure 12 [9,11,12], again because of the much lower 14 N hfs compared to Á CH 2 COOH, 14.8 versus 16.0 G. It is reasonable to assume that the additional adduct in CF 2 HCOOH and in PFEESA is derived from Á OH reaction at the acid end group or corresponding anion. A recent kinetic study of the reaction of Á OH radicals with a homologous series of perfluorinated acids of the general formula F(CF 2 ) n COOH with n = 1-4 in the gas phase at 296 K has provided evidence for the activation of acid groups to Á OH attack by CF 2 or CF 3 groups [82].…”

Section: The Carbon-centred Dmpo Adductsmentioning

confidence: 98%

Fragmentation of Fluorinated Model Compounds Exposed to Oxygen Radicals: Spin Trapping ESR Experiments and Implications for the Behaviour of Proton Exchange Membranes Used in Fuel Cells

2008

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Low-molecular weight model compounds (MCs) for Nafion membranes used in fuel cells were exposed at 300 K to Á OH radicals produced by UV irradiation of aqueous H 2 O 2 solutions. The MCs contained fluorinated and partially fluorinated groups terminated by sulphonic or carboxylic acid groups. The fragmentation process in the MCs was studied by spin trapping electron spin resonance (ESR) methods, using 5,5-dimethylpyrroline-N-oxide (DMPO), N-tert-butyla-phenylnitrone (PBN) and 2-methyl-2-nitrosopropane (MNP) as the spin traps. The objective of these experiments was to assess the effect of the type of ionic groups (sulphonic or carboxylic) and of fluorine substitution on the spin adducts detected. DMPO experiments led to the detection of spin adducts of Á OH and of carbon-centred radicals (CCRs), and allowed the determination of the Á OH attack site on the ionic and/or on the protiated or fluorinated groups. CCR adducts were also detected when using PBN as a spin trap; a key point in the interpretation of the PBN results was, however, the realisation that MNP is formed during PBN exposure to UV irradiation and oxygen or other oxidants such as H 2 O 2 . Experiments with MNP as the spin trap were the most informative in terms of structural details for adducts obtained from each MC. The results allowed the identification of CCRs present as adducts, based on large hyperfine splittings (hfs) from, and the number of, interacting 19 F nuclei; in addition, oxygen-centred radicals (OCRs) as MNP adducts were also identified, with much lower hfs from 19 F nuclei. Taken together, the results deduced by spin trapping suggest that both sulphonic acid and acetic acid groups can be attacked by Á OH radicals and confirm two possible degradation mechanisms in Nafion membranes: initiated at the backbone and at the side chain.

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Section: The Carbon-centred Dmpo Adductsmentioning

confidence: 98%

Fragmentation of Fluorinated Model Compounds Exposed to Oxygen Radicals: Spin Trapping ESR Experiments and Implications for the Behaviour of Proton Exchange Membranes Used in Fuel Cells

2008

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“…Attempts have been made to grow CNTs directly on to the carbon paper to form a GDL [15][16][17][18][19][20][21] and as catalyst support. [22][23][24][25][26][27][28][29][30][31][32] The present study however targets the carbon paper for enhanced performance using a novel and simple technique of CNT incorporation without any additional cost or elaborate setup. This will go a long way in rendering a cost competitive and industrially viable technology.…”

Section: -14mentioning

confidence: 99%

Enhanced performance of PEM fuel cell using MWCNT reinforced carbon paper

Maheshwari

Mathur

2014

RSC Adv.

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Porous conducting carbon paper has been identified as one of the most suitable materials to be used as a fuel cell electrode backing. Carbon paper is prepared by the combined process of papermaking followed by composite formation. Experiments have been carried out whereby heat treated multiwalled carbon nanotubes (MWCNTs) are integrated in the sample while keeping the amount of fiber and resin constant.The diminutive magnitudes of these nanostructures are found to have a considerable effect on the electrical and mechanical properties of the carbon paper electrode. The I-V performance of the unit polymer electrolyte membrane (PEM) fuel cell shows a maximum power density of 880 mW cm À2 with 0.05 vol% of MWCNTs, an increase of $25% as compared to 700 mW cm À2 obtained using commercially available standard Toray carbon paper tested under similar conditions.

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“…Carbon black is a type of carbon material with widespread applications such as reinforcing compounds in rubbers [1,2], electrically conductive agents in plastics [3,4], and as catalyst support in proton exchange membrane fuel cells [5,6]. Several types of carbon blacks exist, including furnace black, channel black, lamp black, thermal black and acetylene black [7].…”

Section: Introductionmentioning

confidence: 99%