Chemical and Electrochemical Parameters for Oxygen Reduction on Pt ‐  H 2 WO 4 / Carbon Electrodes in 99 %  H 3 PO 4

Essalik, A.; Savadogo, O.; Ajersch, F.

doi:10.1149/1.2048584

Cited by 14 publications

(4 citation statements)

References 10 publications

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“…The value of about 40 kJ /mol for T ≤ 90 • C lies within the range of 40-72 kJ mol −1 reported in the literature. 7,[98][99][100] In the presence of [2-Sea + ][TfO − ], the apparent activation energy decreases dramatically from about 68 kJ mol −1 (T < 90 • C) to 9 kJ mol −1 (T > 90 • C). In theory, the same factors could be responsible for this effect as those discussed in the last paragraph.…”

Section: Resultsmentioning

confidence: 99%

2-Sulfoethylammonium Trifluoromethanesulfonate as an Ionic Liquid for High Temperature PEM Fuel Cells

Wippermann

Wackerl

Lehnert

et al. 2015

J. Electrochem. Soc.

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Tafel Oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFC).-High temperature polymer electrolyte fuel cells (HT-PEFCs) are currently based on phosphoric acid-doped polybenzimidazole-type membranes (PBI) and are operated in a temperature range of 120-180• C. HT-PEFCs have several advantages over low temperature PEFCs, such as: easier water and heat management, the possibility of recovering high-grade waste heat, a more compact cooling system and a higher CO tolerance by the anode catalyst.However, a major drawback of HT-PEFCs is the sluggish oxygen reduction reaction (ORR) kinetics in the presence of phosphoric acid. This is primarily caused by three effects: (i) The inhibition effect of phosphoric acid on the ORR because of the poisoning of the Pt catalyst due to the adsorption of the H 3 PO 4 species onto active catalyst sites. (ii) The low solubility of oxygen in phosphoric acid. (iii) The slow diffusion of oxygen through the film of phosphoric acid which covers the platinum catalyst.The adsorption of phosphate by platinum has been studied for more than 30 years 1-15 by means of cyclic voltammetry (CV), [2][3][4][5]9,[11][12][13][14][16][17][18][19][20][21] rotating disc electrode measurements (RDE), [2][3][4][5]8,9,11,13,14 electrochemical impedance spectroscopy (EIS), 13,16,22 transient measurements, 9,23,24 Fourier transform infrared spectroscopy (FTIR), 20,25-27 electrochemical quartz crystal microbalance (QCM), 18 radio tracer experiments, 28 X-ray photoelectron spectroscopy (XPS) 17 and X-ray absorption spectroscopy (XAS). 14,15 The in-operando XAS measurements recently published by Kaserer et al. show the adsorption behavior of H 3 PO 4 species on Pt/C fuel cell cathode catalysts in the temperature range of 50-170• C under the operating conditions of an HT-PEFC. 15In diluted aqueous solutions and at moderate temperatures, sulphuric acid and sulfonic acids like methanesulfonic acid (MSA) or trifluoromethanesulfonic acid (triflic acid, TFMSA) have been found to be less poisonous than phosphoric acid because sulfonate groups are less strongly adsorbed on Pt. 3,29,30 For example, Zelenay et al.,29 in a comparative study of phosphoric acid and TFMSA, showed that * Electrochemical Society Active Member. z E-mail: k.wippermann@fz-juelich.de 0.02 M TFMSA is indeed less strongly adsorbed by comparison to 0.02 M phosphoric acid at room temperature. However, the free space available for oxygen reduction is found to be similar at elevated temperatures and for concentrated solutions. 29 Under these conditions, the advantage of TFMSA lies in its higher oxygen solubility and diffusivity rather than its poisoning effect. 29 Although this result cannot be generalized, it still indicates the importance of oxygen solubility and the diffusion coefficient of oxygen in the electrolyte being used. Proton conducting ionic liquids (PIL).-With respect to alternative electrolytes for HT-PEFCs, proton-conducting ionic liquids (PILs) appear to be suitable, as they do not rely on solvents like water. Moreover...

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Section: Resultsmentioning

confidence: 99%

2-Sulfoethylammonium Trifluoromethanesulfonate as an Ionic Liquid for High Temperature PEM Fuel Cells

Wippermann

Wackerl

Lehnert

et al. 2015

J. Electrochem. Soc.

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“…Recently, it was shown that heteropolyacids can be suitably anchored on active carbon supports and used as catalysts in heterogeneous oxidation reactions [92]. Tungstic acid (H 2 WO 4 ) has been employed as a catalytic enhancer for Pt in phosphoric acid fuel cells by a simple blending procedure during electrode preparation [93]. This suggests that a novel route to increase the overall reaction rate could be based on the use of heteropoly-metallates as substrate species in conjunction with Pt-Ru catalysts.…”

Section: Heteropolyacids As Surface Promotersmentioning

confidence: 99%

DMFCs: From Fundamental Aspects to Technology Development

Aricò¹,

Srinivasan

Antonucci³

2001

Fuel Cells

1,458

884

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This review paper describes recent developments in both the fundamental and technological aspects of direct methanol fuel cells (DMFCs). Most previous studies in this field have dealt with fundamental aspects, whereas in recent years, the technology of these devices has become the object of significant interest. This is mainly due to the fact that a probable application of DMFCs in portable power sources and in hybrid electrical vehicles has only recently been envisaged. The section on fundamentals is particularly focused on the electrocatalysis of the methanol oxidation reaction and oxygen electroreduction. In this regard, particular relevance is given to the interpretation of the promoting effect on Pt of additional elements and some aspects of the electrocatalysis of oxygen reduction in the presence of methanol crossover have been treated. The technology section deals with the development of both components and devices. Particular emphasis is given to the development of high surface area electrocatalysts and alternative electrolyte membranes to Nafion, also the fabrication methodologies for the M&E assembly have been discussed. The last part of the paper describes the recent efforts in developing DMFC stacks for both portable and electro‐traction applications. The current status of the technology in this field is presented and some important technical and economical challenges are been discussed.

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“…The evaluation of the number of the electrons transferred during the reaction was calculated from the Koutecky-Levich plots at different potentials in the mixed diffusion control region assuming C O2 = 1.1 10 -3 M, D O2 = 1.9 10 -5 cm 2 s -1 and υ = 1.009 10 -2 cm 2 s -1 , as reported in ref. (19).…”

Section: Resultsmentioning

confidence: 99%

Increased Selectivity Towards Oxygen Reduction Reaction in the Presence of Methanol by Incorporation of Tungsten Oxides and Platinum

Calderón¹,

Salgado²,

Morales³

et al. 2010

ECS Trans.

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Platinum-tungsten oxides supported on Vulcan carbon were incorporated by means of an impregnation method. XRD and TEM-EDX results indicated that the material is formed by a mixture of tungsten trioxide and platinum particles supported on carbon. XPS analysis showed the presence of tungsten trioxide, metallic platinum and platinum oxides (PtO and PtO 2 ) on the surface of the material. The catalytic performance of PtWO x /C and Pt/C for the oxygen reduction reaction (ORR) was analyzed in the absence and presence of methanol throughout cyclic voltammetry and rotating disk electrode. The results indicated that the addition of tungsten trioxide increases both the catalytic performance of the ORR and catalyst's methanol tolerance.

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Chemical and Electrochemical Parameters for Oxygen Reduction on Pt ‐ H 2 WO 4 / Carbon Electrodes in 99 % H 3 PO 4

Cited by 14 publications

References 10 publications

2-Sulfoethylammonium Trifluoromethanesulfonate as an Ionic Liquid for High Temperature PEM Fuel Cells

2-Sulfoethylammonium Trifluoromethanesulfonate as an Ionic Liquid for High Temperature PEM Fuel Cells

DMFCs: From Fundamental Aspects to Technology Development

Increased Selectivity Towards Oxygen Reduction Reaction in the Presence of Methanol by Incorporation of Tungsten Oxides and Platinum

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