Hydrogen sulfide poisoning and recovery of PEMFC Pt-anodes

Shi, Weiyu; Yi, Baolian; Hou, Ming; Jing, Fenning; Ming, Pingwen

doi:10.1016/j.jpowsour.2006.12.052

Cited by 51 publications

(42 citation statements)

References 13 publications

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“…This is very similar to data reported by Shi et al [26] for performances measured at a constant operating current after each poisoning and recovery cycles. However, the performance loss between the second the third exposures is minimal.…”

Section: H 2 S Adsorption Under Load Conditionssupporting

confidence: 92%

“…This performance data if obtained as a function of bulk H 2 S concentration and adsorption potential (by controlling the cell potential) can be used to estimate the rate of increase in S coverage (i.e., S adsorption on Pt). One must note that most transient performance data obtained on a PEM fuel cell anode reported in the literature [5,14,26,39] are those recorded at a constant operating current and not at a constant operating potential. Under galvanostatic conditions, the local overpotential increases to values as high as the open circuit potential and therefore, the fuel cell can sustain a much larger time of operation.…”

Section: H 2 S Adsorption Under Load Conditionsmentioning

confidence: 99%

“…There are two contradicting reports in the literature about the issue of sulfur induced altering of ionic resistances in a PEM fuel cell. Shi et al [26] have reported that the fuel cell resistance is independent of sulfur contamination and that only the kinetics is affected. They recorded the high frequency cell resistance at various stages of H 2 S exposure and the result was scattered (i.e., a trend was not observed).…”

Section: Figure 3: Current-potential Curves Obtained With Pure H 2 Anmentioning

confidence: 99%

“…In summary, the following could be deduced from the literature reports on the kinetics of H 2 S adsorption and oxidation, both in liquid phase {planar [7][8][9][10][11][12][13] and composite [21,25,26,27] electrodes} and in gas phase {planar [15][16][17][18][19][20][21] and composite electrodes [3,5,6,[22][23][24]25]}, a. H 2 S adsorption on Pt is dissociative, and results in surface adsorbed sulfur species and hydrogen. The hydrogen thus formed undergoes oxidation at positive electrode potentials.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of sulfur poisoning on a PEM fuel cell electrode

Sethuraman

Weidner

2010

Electrochimica Acta

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The extent of irreversible deactivation of Pt towards hydrogen oxidation reaction (HOR) due to sulfur adsorption and subsequent electrochemical oxidation is quantified in a functional PEM fuel cell. At 70 °C, sequential hydrogen sulfide (H 2 S) exposure and electrochemical oxidation experiments indicate that as much as 6% of total Pt sites are deactivated per monolayer sulfur adsorption at open circuit potential of a PEM fuel cell followed by its removal. The extent of such deactivation is much higher when the electrode is exposed to H 2 S when the fuel cell is operating at a finite load, and is dependent on the local overpotential and the duration of exposure. Regardless of this deactivation, the H 2 /O 2 polarization curves obtained on postrecovery electrodes do not show performance losses suggesting that such performance curves alone cannot be used to assess the extent of recovery due to sulfur poisoning. A concise mechanism for the adsorption and electro-oxidation of H 2 S on Pt anode is presented. H 2 S dissociatively adsorbs onto Pt as two different sulfur species and at intermediate oxidation potentials, undergoes electro-oxidation to sulfur and then to sulfur dioxide (SO 2 ). This mechanism is validated by charge balances between hydrogen desorption and sulfur electrooxidation on Pt. The ignition potential for sulfur oxidation decreases with increase in temperature, which coupled with faster electro-oxidation kinetics result in the easier removal of adsorbed sulfur at higher temperatures. Furthermore, the adsorption potential is found to influence sulfur coverage of an electrode exposed to H 2 S. As an implication, the local potential of a PEM fuel cell anode exposed to H 2 S contaminated fuel should be kept below the equilibrium potential for sulfur oxidation to prevent irreversible loss of Pt sites.

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Section: H 2 S Adsorption Under Load Conditionssupporting

confidence: 92%

Section: H 2 S Adsorption Under Load Conditionsmentioning

confidence: 99%

Section: Figure 3: Current-potential Curves Obtained With Pure H 2 Anmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of sulfur poisoning on a PEM fuel cell electrode

Sethuraman

Weidner

2010

Electrochimica Acta

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“…To date, several methods have been performed to handle this problem. Recovery of the cell performance could be completely achieved with methods of cyclic voltammetry (CV), voltage pulse and a driven cell [1][2][3][4]. However, these measures were difficult to be implemented during the normal cell operation.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the electrochemical removal of SO2 in ambient air for proton exchange membrane fuel cells

Zhai¹,

Hou²,

Shao³

et al. 2012

Electrochemistry Communications

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Effects of contaminants on catalyst activity

Garzón

Uribe

2010

Handbook of Fuel Cells

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Hydrogen fuel and ambient air contaminants that exhibit strong electrode catalyst chemisorption may severely degrade the performance of polymer membrane fuel cells. Common fuel‐reforming impurities include carbon monoxide and hydrogen sulfide and air impurities include sulfur oxides and nitrogen oxides. CO contamination at parts per million (ppm) levels severely affects fuel cell performance; however, a number of methods including depolarization, air bleeding, and CO tolerant catalyst alloys will mitigate the performance losses. In contrast, the deposition of S on Pt surface from adsorption of sub‐ppm levels of H 2 S in the H 2 ‐fuel stream results in severe fuel cell performance degradation. The oxidative removal of adsorbed S is a kinetically hindered process and is not achievable at reasonable rates in normal fuel cell operation.

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Hydrogen sulfide poisoning and recovery of PEMFC Pt-anodes

Cited by 51 publications

References 13 publications

Analysis of sulfur poisoning on a PEM fuel cell electrode

Analysis of sulfur poisoning on a PEM fuel cell electrode

Investigation on the electrochemical removal of SO2 in ambient air for proton exchange membrane fuel cells

Effects of contaminants on catalyst activity

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