The nature of species adsorbed on platinum from SO2 solutions

Contractor, A.Q.; Lal, Hira

doi:10.1016/s0022-0728(78)80222-8

Cited by 28 publications

(40 citation statements)

References 10 publications

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“…At 80 • C, it has been shown that two features exist in the oxygen adsorption region of the voltammograms; it has been postulated that these features represent a linear and bridged form of sulfur on the Pt surface, signifying both a weakly and strongly bonded sulfur species [16,22,23]. These two sulfur oxidation peaks occur at 0.97 and 1.10 V. Three oxidation peaks were observed in our work (I-III).…”

Section: Resultssupporting

confidence: 50%

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Deactivation of Pt/VC proton exchange membrane fuel cell cathodes by SO2, H2S and COS

Gould

Батурина

Swider‐Lyons

2009

Journal of Power Sources

103

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Section: Resultssupporting

confidence: 50%

“…Sulfur species adsorbed on the Pt can be electrochemically oxidized to water-soluble sulfate by a six-electron process with water at potentials greater than about 0.8 V vs. a reversible hydrogen electrode, by the reaction in Eq. (1) [14][15][16]:…”

Section: Introductionmentioning

confidence: 99%

Deactivation of Pt/VC proton exchange membrane fuel cell cathodes by SO2, H2S and COS

Gould

Батурина

Swider‐Lyons

2009

Journal of Power Sources

103

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“…30 It was reported that the electrochemical oxidation of S ad to sulfate in aqueous phase required potential cycling up to 1.5 V, 24 suggesting that the reactivation of Pt surface by electrochemical desorption of S ad was very difficult in typical PEMFC operating conditions. Therefore, in this study it seemed that the Pt surface blocked by S ad with significant voltage decay at high SO 2 concentration was not fully recovered, because the cell voltage was maintained below 1.0 V, which probably resulted in incomplete recovery of cell voltage as shown in Figure 3(b) (indicated by ).…”

mentioning

confidence: 99%

Systematic Analysis for the Effects of Atmospheric Pollutants in Cathode Feed on the Performance of Proton Exchange Membrane Fuel Cells

Yoon

Choi

Lee³

et al. 2014

Bulletin of the Korean Chemical Society

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This paper describes how primary contaminants in ambient air affect the performance of the cathode in fuel cell electric vehicle applications. The effect of four atmospheric pollutants (SO 2 , NH 3 , NO 2 , and CO) on cathode performance was investigated by air impurity injection and recovery test under load. Electrochemical analysis via polarization and electrochemical impedance spectroscopy was performed for various concentrations of contaminants during the impurity test in order to determine the origins of performance decay. The variation in cell voltage derived empirically in this study and data reported in the literature were normalized and juxtaposed to elucidate the relationship between impurity concentration and performance. Mechanisms of cathode degradation by air impurities were discussed in light of the findings.

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“…Seo and Sawyer 5 suggested that the oxidation of SO2 proceeds in two steps: one a pure electron transfer process and the other a chemical oxidation by electrolytically formed metal oxides. Lal and coworkers 7,8 reported that SO2 is reduced via an SO intermediate which can be singly-or doubly-bonded to the surface. From studies in concentrated sulfuric acid, Applyby and Pichon 6 suggested SO2 is oxidized to sulfuric acid via the formation of dithionate as a rate-determining step.…”

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confidence: 99%

Electrocatalytic Oxidation of Sulfur Dioxide by Iron Phthalocyanine Monolayer in Aqueous Solutions

Kim¹

2002

Bulletin of the Korean Chemical Society

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The SO2 oxidation has been paid much attention due to its technological applications in the field of energy production, 1 flue gas desulfurization, 2 and electrowinning of sulfide ores.3 Most work so far has been done using pure metal, particularly platinum and gold electrodes [4][5][6] in aqueous solutions. The reactions on these surfaces are highly complicated depending on many factors such as surface pre-treatment, potential range excursed, and the presence of oxides films and thus there is not quite an agreement about the kinetics and mechanisms. Seo and Sawyer 5 suggested that the oxidation of SO2 proceeds in two steps: one a pure electron transfer process and the other a chemical oxidation by electrolytically formed metal oxides. Lal and coworkers 7,8 reported that SO2 is reduced via an SO intermediate which can be singly-or doubly-bonded to the surface. From studies in concentrated sulfuric acid, Applyby and Pichon 6 suggested SO2 is oxidized to sulfuric acid via the formation of dithionate as a rate-determining step. Recent studies appear to suggest the formation of dithionate ion in weakly acidic to weakly basic solutions. Katagiri and Matsubara suggested 9 that Cu(II) ion catalyzes SO3 2− oxidation to S2O6 2− via the formation of binuclear Cu(II) complex by Raman spectroscopy. From radiotracer study, Vargar et al. 10 suggested the oxidation of SO2 to S2O6 2− on a gold electrode. While most researches to date have been carried out on metal surfaces, the electrocatalytic oxidation of SO2 by adsorbed macrocycles has not been studied to our knowledge. There is only a report on the electrochemical transformation of sulfur oxoanions using water-soluble iron porphyrins. 11We have been working on electrocatalytic reactions of NOx and SOx using metallo-phthalocyanines. Among them, iron phthalocyanine (FePc) was proven to be particularly effective for NO and SO2 reduction reactions 12-14 when adsorbed on the surface. The electronic and structural changes upon the surface 15,16 as well as in a sol-gel matrix 17 have also been studied in our group. Based on these previous works, we have tried in this paper the oxidation of SO2 by the adsorbed FePc monolayer on the electrode surface in aqueous solutions as a function of pH. Experimental SectionAll the chemicals were of analytical grade and used without further purification. The SO2 concentration was controlled by adding concentrated sodium sulfite solution (1.0 M) to the electrolyte. 18 M deionized water (Millipore Co.) was used to prepare solutions. Adsorption of FePc (Aldrich) onto the edge plane of OPG (ordinary pyrolytic graphite, Union Carbide) was effected by dipping the electrode in a FePc-dissolved DMSO solution. The working electrode was made by molding an OPG piece into the Kel-F plastic and exposing the edge plane. In each experiment, the electrode was ground against 2000-grit SiC paper to ensure the fresh surface.Electrochemical measurements were performed with a typical three-electrode system and a potentiostat (Autolab PGSTAT 30, ECO CHEM). A A...

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The nature of species adsorbed on platinum from SO2 solutions

Cited by 28 publications

References 10 publications

Deactivation of Pt/VC proton exchange membrane fuel cell cathodes by SO2, H2S and COS

Deactivation of Pt/VC proton exchange membrane fuel cell cathodes by SO2, H2S and COS

Systematic Analysis for the Effects of Atmospheric Pollutants in Cathode Feed on the Performance of Proton Exchange Membrane Fuel Cells

Electrocatalytic Oxidation of Sulfur Dioxide by Iron Phthalocyanine Monolayer in Aqueous Solutions

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