Potential dependence of sulfur dioxide poisoning and oxidation at the cathode of proton exchange membrane fuel cells

Fu, Jie; Hou, Ming; Du, Chao; Shao, Zhigang; Yi, Baolian

doi:10.1016/j.jpowsour.2008.10.103

Cited by 69 publications

(51 citation statements)

References 12 publications

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“…Among the ordinary contaminants, sulfur-contained compounds are one of the most severely poisons that affect the performance [3][4][5]. Thus a lot of studies have been performed on the poisoning behavior of SO 2 , and exploring the impacts of temperature, humidity, potential and concentration of SO 2 under operating conditions in order to get the recovery strategies [5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

A quantitative research on S- and SO2-poisoning Pt/Vulcan carbon fuel cell catalyst

Xie

Shao

Zhang

et al. 2012

Electrochimica Acta

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a b s t r a c tA quantitative research on S and SO 2 poisoning Pt/Vulcan carbon (Pt/VC) catalysts for fuel cells was conducted by the three-electrode method. Pt/VC electrodes were contaminated by submersion in a SO 2 -containing solution made up of 0.2 mM Na 2 SO 3 and 0.5 M H 2 SO 4 for different periods of time, and held at 0.05 V (vs. RHE) in 0.5 M H 2 SO 4 solutions in order to gain zero-valence sulfur (S 0 ) poisoned electrodes. The sulfur coverage of Pt was determined from the total charge consumed as the sulfur was oxidized from S 0 at 0.05 V (vs. RHE) to sulfate at >1.1 V (vs. RHE). The summation of initial coverage of S 0 (Â S ) and coverage of H (Â H ) are approximately equal to 1 (Â H + Â S = 1) when 0.5 < Â H < 1, which gives an easy way to figure out the quantity of sulfur adsorbed on Pt/VC. As to SO 2 poisoned Pt/VC, the catalytic activity of oxygen reduction reaction (ORR) decreases linearly with the amount of SO 2 adsorbed on the Pt nanoparticles when 0.45 < Â H < 0.81. When the adsorbed SO 2 was reduced to S 0 , the mass activity was greatly recovered, and the area specific activity was even higher than the unpoisoned Pt/VC.

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Section: Introductionmentioning

confidence: 99%

A quantitative research on S- and SO2-poisoning Pt/Vulcan carbon fuel cell catalyst

Xie

Shao

Zhang

et al. 2012

Electrochimica Acta

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“…SO 2 has been reported as a poison in a number of air-contaminant studies, where it is exposed to the cathode sides of a working fuel cell [30,31,32]. It has been shown that SO 2 adsorbs strongly to Pt.…”

Section: Introductionmentioning

confidence: 99%

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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“…According to the report in Ref. [6], the reduced hydrogen-desorption peak is attributed to SO 2 adsorption and occupation on active sites of the cathode catalyst. The large oxidation peak is formed when the potential reaches about 1.1 V, at which SO 2 adsorption on platinum catalyst is electro-oxidized.…”

Section: Methodsmentioning

confidence: 90%

“…The modes of SO 2 adsorption on the platinum catalyst were distinguished into linear adsorption and bridged adsorption [5]. Fu et al [6] investigated the potential dependence of SO 2 poisoning and oxidation. They suggested that SO 2 molecules could be adsorbed on the Pt catalyst without charge transfer at 0.65 V, oxidized above 0.65 V and reduced below it.…”

Section: Introductionmentioning

confidence: 99%