Influence of Nafion® ionomer on carbon corrosion

Cherstiouk, Olga V.; Simonov, P.A.; Фенелонов, В. Б.; Savinova, Elena R.

doi:10.1007/s10800-010-0169-8

Cited by 13 publications

(11 citation statements)

References 36 publications

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“…A comparison of the three MEAs revealed that the fuel cell degradation rates were dependent on the electrode layer composition. The high catalyst and Nafion coating loadings likely provide a durable electrode structure because Nafion has been shown to prevent carbon corrosion [89]. The obtained data demonstrated a CO tolerance of the Fe/N/C cathodes, confirming previously published data where CO effects were studied using RDE techniques [29,30].…”

Section: Effect Of Co On a Fuel Cell Performancesupporting

confidence: 85%

Tolerance of non-platinum group metals cathodes proton exchange membrane fuel cells to air contaminants

Reshetenko

Serov

Artyushkova

et al. 2016

Journal of Power Sources

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The effects of major airborne contaminants (SO 2 , NO 2 and CO) on the spatial performance of Fe/N/C cathode membrane electrode assemblies were studied using a segmented cell system.The injection of 2-10 ppm SO 2 in air stream did not cause any performance decrease and redistribution of local currents due to the lack of stably adsorbed SO 2 molecules on Fe-N x sites, as confirmed by density functional theory (DFT) calculations. The introduction of 5-20 ppm of CO into the air stream also did not affect fuel cell performance. The exposure of Fe/N/C cathodes to 2 and 10 ppm NO 2 resulted in performance losses of 30 and 70-75 mV, respectively.DFT results showed that the adsorption energies of NO 2 and NO were greater than that of O 2 , which accounted for the observed voltage decrease and slight current redistribution. The cell performance partially recovered when the NO 2 injection was stopped. The long-term operation of the fuel cells resulted in cell performance degradation. XPS analyses of Fe/N/C electrodes revealed that the performance decrease was due to catalyst degradation and ionomer oxidation.The latter was accelerated in the presence of air contaminants. The details of the spatial performance and electrochemical impedance spectroscopy results are presented and discussed. stream [7,8,[10][11][12][13][14][15][16][17][18][19]. The effects of nitrogen-containing air contaminants (NO x , NH 3 ) were found to be moderate and recoverable [7,8,[10][11][12][13][14][15][16][20][21][22][23][24].However, there have been limited studies on the impact of air contaminants, such as CO, SO 2 , and NO x , on the performance of non-PGM catalysts. Impacts of CO on the ORR activity of Fe/N/C catalysts were reported in [25][26][27][28][29][30]. Common precursors for Fe/N/C, such as Fe-porphyrin and Fe-phthalocyanine, are well-known to have a higher affinity for CO than O 2 . Therefore, the Fe-N 4 /C and Fe-N 2 /C sites in catalysts were expected to strongly chemisorb CO. However, it was observed that steric factors of ligands in Fe-porphyrin complexes can reduce affinity to CO or even suppress any CO binding at atmospheric pressure [25,26]. Moreover, studies of Feporphyrin interactions with CO in aqueous solutions by in situ X-ray absorption showed the formation of CO-Fe-porphyrin adduct, which disappeared at a 0.6 V potential, released the CO molecules [27]. Recent studies have showed CO tolerance of iron-containing catalysts [28][29][30].In attempts to identify active sites on Fe/N/C catalysts, CNwas observed to have strong poisoning effects [31][32][33]. The authors indicated that CNbound at an axial position on the sites, inhibiting oxygen reduction and shifting the reaction pathway from 4-electron to 2-electron.Remarkably, catalytic activity was restored after rinsing a poisoned electrode in water [33]. SO 2 tolerance was reported for ORR catalysts wherein Fe was encapsulated in carbon nanotubes [34].Fe/N/C catalysts derived from poly-m-phenylenediamine were found to be insensitive to NO x , whereas oxygen reduction was su...

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Section: Effect Of Co On a Fuel Cell Performancesupporting

confidence: 85%

Tolerance of non-platinum group metals cathodes proton exchange membrane fuel cells to air contaminants

Reshetenko

Serov

Artyushkova

et al. 2016

Journal of Power Sources

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“…However, Nafion® molecules are complex entities, which participate in a variety of interactions involving their polar (ether and sulfonic) and non-polar (perfluorinated backbone) groups. The previous papers [37,38,41] reported actual Nafion® quantities on the Vulcan surface in presence of ionomer's liquid solutions. To the contrary, the voltammetric technique used in our study ( Fig.…”

Section: The Effect Of Nafion On the Electrochemical Behavior Of Vulcmentioning

confidence: 99%

“…However, the ability of Nafion® to act as a surfactant indicates the existence of specific interactions between the catalyst/support particles and the ionomer. In fact, a strong monolayer Nafion® adsorption from liquid solutions on a variety of carbon supported Pt catalysts and catalyst supports has been demonstrated [37][38][39][40][41]. While the respective catalyst activities have not been reported [37][38][39][40], the voltammograms of carbon nanotube (CNT) supported Pt catalysts in Ref.…”

Section: Introductionmentioning

confidence: 99%

On the use of Nafion® in electrochemical studies of carbon supported oxygen reduction catalysts in aqueous media

Chlistunoff

Sansiñena

2016

Journal of Electroanalytical Chemistry

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The paper presents the results of a voltammetric and rotating ring disk electrode (RRDE) study of oxygen reduction reaction (ORR) catalyzed by Fe and Co porphyrins and phthalocyanines adsorbed on a high surface area carbon (Vulcan XC72) and by carbon supported Pt catalysts in presence of various quantities of Nafion®. The results demonstrate that the hydrophobic backbone of Nafion® self assembles on nanoparticles of common carbon supports of ORR catalysts. The phenomenon is promoted by the attractive interactions of the backbone with the graphitic surfaces of carbon particles. It leads to a significant ORR inhibition as a result of the spillover of the hydrophobic Nafion® component onto the catalyst particles. The extent of the inhibition depends on the type and the amount of the catalyst on the carbon surface and the degree of carbon surface graphitization. The activity of the transition metal macrocycles is suppressed by up to two orders of magnitude, whereas that of low Pt loading (4.8%) catalysts by less than one order of magnitude. The results demonstrate a great risk of incorrect catalyst activity determinations when using even very small Nafion® quantities as the catalyst ink dispersing agent.

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“…Carbon specimen was suspended in 2 ml of isopropanol:water (3:2) mixture and sonicated in an ultrasonic bath for 15 min, then an aliquot of the Nafion® dispersion in water was added and the mixture was sonicated for another 15 min. Because the corrosion current densities obey inverted volcano‐like dependence on the amount of Nafion® with a minimum at ∼0.8 mg Nafion m

_{−2}^{carbon}

16 in this work the corresponded quantity of Nafion® was added to suspension (∼0.8* A BET ). Samples were dried during 1.5 h in a furnace at 105 ± 1 °C and then mounted in the electrochemical cell.…”

Section: Experimental and Methodologymentioning

confidence: 99%

Electrocorrosion properties of multiwall carbon nanotubes

Cherstiouk

Кузнецов

Simonov

et al. 2010

Physica Status Solidi (b)

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Phone: þ7 383 330 87 65, Fax: þ7 383 326 97 50, Web: www.catalysis.ruThe electrochemical corrosion properties of a set of multiwalled carbon nanotubes (MWCNT) with different average diameters (hdi ¼ 7-22 nm) and conventional carbon black Vulcan XC-72 were studied potentiostatically in 2 M H 2 SO 4 at 80 8C. Effects of grinding and high-temperature treatment (2800 8C) in inert gas on the corrosion stability of MWCNT were also examined. Excitation of MWCNTs with large hdi in activator mill results in local disruption of the fine structure of the NTs and increase of the corrosion current densities. No rupture and changes of the corrosion behaviour occur for MWCNTs with lower hdi after grinding. High-temperature treatment of MWCNTs leads to removal of amorphous carbon and defects from the surface of the materials and results in drastic decrease of the reactivity of the surface of the materials towards electrocorrosion. The A BET -weighted corrosion current densities of the MWCNTs are significantly lower than that of conventional XC-72 material evidencing of their higher stability towards electrocorrosion.

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Influence of Nafion® ionomer on carbon corrosion

Cited by 13 publications

References 36 publications

Tolerance of non-platinum group metals cathodes proton exchange membrane fuel cells to air contaminants

Tolerance of non-platinum group metals cathodes proton exchange membrane fuel cells to air contaminants

On the use of Nafion® in electrochemical studies of carbon supported oxygen reduction catalysts in aqueous media

Electrocorrosion properties of multiwall carbon nanotubes

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