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High resolution mapping of oxygen reduction reaction kinetics at polycrystalline platinum electrodes
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Chen, Chang-Hui, Meadows, Katherine E., Cuharuc, Anatolii S., Lai, Stanley Chi Shing and Unwin, Patrick R. (2014) High resolution mapping of oxygen reduction reaction kinetics at polycrystalline platinum electrodes. Physical Chemistry Chemical Physics, Volume 16 (Number 34). pp. 18545-18552. doi:10.1039/c4cp01511h
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WRAP_1155473-ch-270515-high_resolution_mapping_of_oxygen_reduction.pdf - Accepted Version - Requires a PDF viewer. Download (1028Kb) | Preview |
Official URL: http://dx.doi.org/10.1039/C4CP01511H
Abstract
The scanning droplet-based technique, scanning electrochemical cell microscopy (SECCM), combined with electron backscatter diffraction (EBSD), is demonstrated as a powerful approach for visualizing surface structure effects on the rate of the oxygen reduction reaction (ORR) at polycrystalline platinum electrodes. Elucidating the effect of electrode structure on the ORR is of major interest in connection to electrocatalysis for energy-related applications. The attributes of the approach herein stem from: (i) the ease with which the polycrystalline substrate electrode can be prepared; (ii) the wide range of surface character open to study; (iii) the possibility of mapping reactivity within a particular facet (or grain), in a pseudo-single-crystal approach, and acquiring a high volume of data as a consequence; (iv) the ready ability to measure the activity at grain boundaries; and (v) an experimental arrangement (SECCM) that mimics the three-phase boundary in low temperature fuel cells. The kinetics of the ORR was analyzed and a finite element method model was developed to explore the effect of the three-phase boundary, in particular to examine pH variations in the droplet and the differential transport rates of the reactants and products. We have found a significant variation of activity across the platinum substrate, inherently linked to the crystallographic orientation, but do not detect any enhanced activity at grain boundaries. Grains with (111) and (100) contributions exhibit considerably higher activity than those with (110) and (100) contributions. These results, which can be explained by reference to previous single-crystal measurements, enhance our understanding of ORR structure-activity relationships on complex high-index platinum surfaces, and further demonstrate the power of high resolution flux imaging techniques to visualize and understand complex electrocatalyst materials.
| Item Type: | Journal Article | ||||||||
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| Subjects: | Q Science > QD Chemistry | ||||||||
| Divisions: | Faculty of Science > Chemistry | ||||||||
| Library of Congress Subject Headings (LCSH): | Electrons— Backscattering, Electrocatalysis , Polycrystals , Chemical kinetics | ||||||||
| Journal or Publication Title: | Physical Chemistry Chemical Physics | ||||||||
| Publisher: | Royal Society of Chemistry | ||||||||
| ISSN: | 1463-9076 | ||||||||
| Official Date: | 8 July 2014 | ||||||||
| Dates: |
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| Volume: | Volume 16 | ||||||||
| Number: | Number 34 | ||||||||
| Number of Pages: | 8 | ||||||||
| Page Range: | pp. 18545-18552 | ||||||||
| DOI: | 10.1039/c4cp01511h | ||||||||
| Status: | Peer Reviewed | ||||||||
| Publication Status: | Published | ||||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||||
| Funder: | European Research Council (ERC), Marie Curie Intra-European Fellowship (IEF) , University of Warwick Vice Chancellor Scholarship | ||||||||
| Grant number: | ERC- 2009-AdG 247143 QUANTIF (ERC) , 275450 VISELCAT (IEF) |
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