ORR Adsorbate Dynamics on Pt Single Crystal PEM Fuel Cells

Dhanda, Abhishek; O’Hayre, Ryan; Pitsch, Heinz

doi:10.1149/1.2981955

Cited by 15 publications

(18 citation statements)

References 29 publications

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“…Because bromomethane and Br were not directly involved in any of the electrochemical transformations at the operating potentials, ORR might cause the observed inductance. The formation of H 2 O 2 as an intermediate product in 2-electron oxygen reduction was previously shown to account for the low-frequency inductive loop [106][107][108]. Therefore, in our case, Br partially shifts the oxygen reduction to a 2-electron mechanism [41] and we could hypothesize that 2-electron ORR resulting in OHand H 2 O 2 formationmay explain the inductance and contribute to ionomer degradation, as was detected by XPS.…”

Section: Discussionsupporting

confidence: 67%

Spatial proton exchange membrane fuel cell performance under bromomethane poisoning

Reshetenko

Artyushkova

St‐Pierre

2017

Journal of Power Sources

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The poisoning effects of5 ppm CH 3 Br in theair on thespatial performance of aproton exchange membrane fuel cell (PEMFC)were studied using a segmented cell system. The presence of CH 3 Brcaused performance loss from 0.650 to 0.335 V at 1 A cm 2 accompanied by local current density redistribution. The observed behavior was explained bypossible bromomethane hydrolysis with the formation of Br . Bromide and bromomethane negatively affected the oxygen reduction efficiencyovera wide range of potentials because oftheir adsorption on Pt, which was confirmed by XPS. Moreover, the PEMFC exposure to CH 3 Br led toa decrease in the anode and cathode electrochemical surface area(~52-57%) due to the growth of Pt particles through agglomeration and Ostwald ripening. The PEMFC did not restore its performance after stopping bromomethane introduction to theair stream. However, the H 2 /N 2 purge of the anode/cathode and CV scans almost completely recovered the cell performance.The observed final loss of ~50 mV was due to an increased activation overpotential. PEMFC exposure to CH 3 Br should be limited to concentrations much less than 5 ppm due to serious performance loss and lack of self-recovery.

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Section: Discussionsupporting

confidence: 67%

Spatial proton exchange membrane fuel cell performance under bromomethane poisoning

Reshetenko

Artyushkova

St‐Pierre

2017

Journal of Power Sources

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“…Evidence for the existence of a doubling of the Tafel slope was recently discussed by Gottesfeld 45 and has been extensively studied experimentally over several decades. 19,27,28,[46][47][48][49][50][51][52][53][54] The results in Figure 17 highlight that the kinetic model has a tremendous impact on MEA model predictions. Therefore, it is essential that an appropriate kinetic model is used in order to study the performance of fuel cell electrodes.…”

Section: Resultsmentioning

confidence: 99%

Understanding the Effect of Kinetic and Mass Transport Processes in Cathode Agglomerates

Moore

Wardlaw

Dobson

et al. 2014

J. Electrochem. Soc.

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A 2D(1D) multi-scale membrane electrode assembly mathematical model is proposed to study the effect of micro-scale transport losses due to catalyst aggregation in the cathode catalyst layer of a fuel cell. In order to develop an analytical expression for micro-scale transport losses, previous agglomerate models assumed an oxygen reduction reaction order of one and neglected any proton transport effects. In this article, a numerical micro-scale spherical ionomer-filled agglomerate model is integrated with a two-dimensional membrane electrode assembly model in order to develop a flexible framework to study different charge, mass, and kinetic transport models that cannot generally be analyzed with an analytical formulation. Results show that there is a significant interplay between scales and that changes in micro-scale agglomerate properties can significantly affect agglomerate effectiveness and current density distributions in the catalyst layer while not significantly affecting overall cell performance. Using the proposed framework, the effects of: a) proton conductivity inside agglomerates, b) a non-equilibrium oxygen dissolution boundary condition, and c) electrochemical models with different oxygen reaction orders, are studied.

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“…This dependence is attributed to the structure sensitive adsorption of intermediate species, such as O ads and OH ads . 88 Many studies showed that low-index planes or facets (111), (100), and (110), typically found on single-crystal surfaces of bulk Pt, have much lower activity than high-index planes. The high-index planes have high densities of atomic steps, ledges, and kinks that act as active sites for breaking chemical bonds.…”

Section: Activitymentioning

confidence: 99%

A comprehensive review of Pt electrocatalysts for the oxygen reduction reaction: Nanostructure, activity, mechanism and carbon support in PEM fuel cells

et al. 2017

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A comprehensive review of Pt electrocatalysts for the oxygen reduction reaction: nanostructure, activity, mechanism and carbon support in PEM fuel cells. Journal of Materials Chemistry A, 5 (5). pp. 1808 -1825 . ISSN 2050 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/40957/1/Journal%20of%20Materials%20Chemistry%20A %EF%BC%88C6TA08580F%20-%20corrected%20proofs%20-final%EF%BC%89.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Translation errors between word-processor files and typesetting systems can occur so the whole proof needs to be read. Please pay particular attention to: tabulated material; equations; numerical data; figures and graphics; and references. If you have not already indicated the corresponding author(s) please mark their name(s) with an asterisk. Please e-mail a list of corrections or the PDF with electronic notes attached -do not change the text within the PDF file or send a revised manuscript. Corrections at this stage should be minor and not involve extensive changes. All corrections must be sent at the same time.Please bear in mind that minor layout improvements, e.g. in line breaking, table widths and graphic placement, are routinely applied to the final version.We will publish articles on the web as soon as possible after receiving your corrections; n no late corrections will be made. The sluggish rate of the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells has been a major challenge. Significantly increasing efforts have been made worldwide towards a highly active ORR catalyst with high durability. Among all the catalysts exploited, Pt electrocatalysts are still the best in terms of a comprehensive evaluation. The investigation of Pt-based ORR catalysts is necessary for a practical ORR catalyst with low Pt content. This paper reviews recent progress in the studies of the mechanism, nanostructure, size effect and carbon supports of Pt electrocatalysts for the ORR. The importance of the size and structure control of Pt ORR catalysts, related with carbon support materials, is indicated. The potential methods for such control are discussed. The progress in theoretical studies and in situ catalyst characterization are also discussed. Finally, challenges and future developments are addressed.

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ORR Adsorbate Dynamics on Pt Single Crystal PEM Fuel Cells

Cited by 15 publications

References 29 publications

Spatial proton exchange membrane fuel cell performance under bromomethane poisoning

Spatial proton exchange membrane fuel cell performance under bromomethane poisoning

Understanding the Effect of Kinetic and Mass Transport Processes in Cathode Agglomerates

A comprehensive review of Pt electrocatalysts for the oxygen reduction reaction: Nanostructure, activity, mechanism and carbon support in PEM fuel cells

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