Electrochemical behaviour of aqueous SO2 at Pt electrodes in acidic medium. A voltammetric and in situ Fourier transform IR study Part I. Oxidation of SO2 on Pt electrodes with sulphur-oxygen adsorbed species

Quijada, C.; Rodes, A.; Vázquez, José Luís; Pérez, José Miguel Giner; Aldaz, A.

doi:10.1016/0022-0728(95)03988-s

Cited by 89 publications

(86 citation statements)

References 30 publications

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“…First of all, according to Garsany et al [13], the adsorbed SO 2 are wholly on the surface of Pt, and the Vulcan carbon does not adsorb SO 2 . Moreover, we already know the relativity between potential and the oxidation state of sulfur [19,[21][22][23][24][25][26]. At the potential of 0.65 V, an unchanged product of SO 2 adsorption was formed on Pt surfaces.…”

Section: Resultsmentioning

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: Resultsmentioning

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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“…For example, when adsorption occurs at potentials lower than 0.55 V vs. SHE on a Pt electrode, the surface coverage approaches 100% [13]. However, when the adsorption potential is raised the coverage starts to decrease as some of the adsorbed SO 2 oxidizes [14]. Coverage of active sites with SO 2 tends to poison the catalyst, inhibiting bulk SO 2 oxidation.…”

Section: Linear Sweep Voltammetrymentioning

confidence: 99%

Catalyst evaluation for a sulfur dioxide-depolarized electrolyzer

Colón-Mercado

Hobbs

2007

Electrochemistry Communications

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Thermochemical processes are being developed to provide global-scale quantities of hydrogen. A variant on sulfur-based thermochemical cycles is the Hybrid Sulfur (HyS) Process which uses a sulfur dioxide depolarized electrolyzer (SDE) to produce the hydrogen. Testing examined the activity and stability of platinum and palladium as the electrocatalyst for the SDE in sulfuric acid solutions. Cyclic and linear sweep voltammetry revealed that platinum provided better catalytic activity with much lower potentials and higher currents than palladium. Testing also showed that the catalyst activity is strongly influenced by the concentration of the sulfuric acid electrolyte. INTRODUCTIONConcerns about the dependence on petroleum imports, poor air quality, and greenhouse emissions have accelerated the development of energy systems using hydrogen as an energy carrier. Hydrogen can be extracted using a variety of technologies, which can be divided in three main categories: thermal, electrochemical, and biological. Among the production methods water electrolysis is a well established technology, which is capable of producing emission free hydrogen if used in conjunction with renewable or nuclear energy [1]. However, the technology and energy inputs for the electrolysis process can make the production of hydrogen by this method expensive. In order to produce global scale quantities of hydrogen in a more energy efficient process, thermochemical water splitting cycles using heat from a nuclear reactor have been proposed and developed since the late 1960s [2].Among the many possible thermochemical cycles for the production of hydrogen, the sulfur-based cycles lead the competition in overall energy efficiency.A variant on sulfur-based thermochemical cycles is the Hybrid Sulfur (HyS) Process. The HyS cycle uses a sulfur dioxide-depolarized electrolyzer (SDE) to produce hydrogen. The electrolyzer oxidizes sulfur dioxide to form sulfuric acid at the anode [r1] and reduces protons to form hydrogen at the cathode [r2]. The overall electrochemical cell reaction consists of the production of H 2 SO 4 and H 2 [r3]. The key attribute of the reactions occurring in the SDE is the anodic reaction [r1], which occurs at a standard half cell potential of -0.158 V vs. standard hydrogen electrode (SHE) [3]. Compared with low temperature pure water electrolysis, which occurs at -1.23 V vs. SHE, the SDE could potentially produce the same amount of hydrogen with almost one eighth of the current used in conventional electrolysis.

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“…The use of perchloric solutions was adopted in spectroscopic experiments to prevent interference from bulk hydrogen sulphate anions. In the spectroscopic runs, an aliquot from a 0.1 M S(IV) +0.5 M HClO 4 stock solution was spiked into the electrolyte-containing spectroelectrochemical cell [9,10]. The concentration of the electroactive species is referred to the total S(IV) initially dissolved.…”

Section: Methodsmentioning

confidence: 99%

“…Sulphur coverage was inferred from the charge passed during the stripping of the isolated adlayer. The isolation of the adlayer was carried out by withdrawal of the electrode from the SO 2 -or sulphide-containing cell, rinsing with ultrapure water and transferral to a secondary cell filled with the background electrolyte [9,11].…”

Section: Methodsmentioning

confidence: 99%

Electrochemical behaviour of aqueous SO2 at polycrystalline gold electrodes in acidic media. A voltammetric and in-situ vibrational study. Part II. Oxidation of SO2 on bare and sulphur-modified electrodes

Quijada

Morallón

Vázquez

et al. 2001

Electrochimica Acta

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The electrochemical oxidation of SO 2 on polycrystalline gold electrodes has been studied by means of cyclic voltammetry and in situ vibrational techniques. On bare gold electrodes, SO 2 is irreversibly oxidised on forward scans at 0.6 V/RHE, featuring a diffusion-limited peak. Oxidation is inhibited by the formation of chemisorbed oxygen. A SO 2 anodic current rise occurs on the reverse scan in parallel with the reduction of the metal oxide layers. As shown by FT-IR, oxidation proceeds to yield a mixture of soluble S(VI) species as stable reaction products. From vibrational spectra and results from the irreversible adsorption method, it follows that no strongly adsorbed S -O-like residues are present onto the gold surface in the region 0.3-0.5 V/RHE. On sulphur-modified electrodes improved electrocatalysis is manifested by the shift of the diffusion-limited peak to lower potentials. The best performance is observed at a sulphur coverage of 0.5. At higher coverage, sulphur adlayers impart lower catalytic efficiency and eventually show strong poisoning properties. This behaviour is exhibited by sulphur adlayers generated either in situ by SO 2 reduction or ex situ by sulphide adsorption/oxidation in acidic or alkaline media.

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Electrochemical behaviour of aqueous SO2 at Pt electrodes in acidic medium. A voltammetric and in situ Fourier transform IR study Part I. Oxidation of SO2 on Pt electrodes with sulphur-oxygen adsorbed species

Cited by 89 publications

References 30 publications

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

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

Catalyst evaluation for a sulfur dioxide-depolarized electrolyzer

Electrochemical behaviour of aqueous SO2 at polycrystalline gold electrodes in acidic media. A voltammetric and in-situ vibrational study. Part II. Oxidation of SO2 on bare and sulphur-modified electrodes

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