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Adsorbate-induced segregation of cobalt from PtCo nanoparticles: modeling Au doping and core AuCo alloying for the improvement of fuel cell cathode catalysts

Farkaš, Barbara, Perry, Christopher B., Jones, Glenn and de Leeuw, Nora H. 2020. Adsorbate-induced segregation of cobalt from PtCo nanoparticles: modeling Au doping and core AuCo alloying for the improvement of fuel cell cathode catalysts. Journal of Physical Chemistry C 124 (33) , pp. 18321-18334. 10.1021/acs.jpcc.0c04460

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Abstract

Platinum, when used as a cathode material for the oxygen reduction reaction, suffers from high overpotential and possible dissolution, in addition to the scarcity of the metal and resulting cost. Although the introduction of cobalt has been reported to improve reaction kinetics and decrease the precious metal loading, surface segregation or complete leakage of Co atoms causes degradation of the membrane electrode assembly, and either of these scenarios of structural rearrangement eventually decreases catalytic power. Ternary PtCo alloys with noble metals could possibly maintain activity with a higher dissolution potential. First-principles-based theoretical methods are utilized to identify the critical factors affecting segregation in Pt–Co binary and Pt–Co–Au ternary nanoparticles in the presence of oxidizing species. With a decreasing share of Pt, surface segregation of Co atoms was already found to become thermodynamically viable in the PtCo systems at low oxygen concentrations, which is assigned to high charge transfer between species. While the introduction of gold as a dopant caused structural changes that favor segregation of Co, creation of CoAu alloy core is calculated to significantly suppress Co leakage through modification of the electronic properties. The theoretical framework of geometrically different ternary systems provides a new route for the rational design of oxygen reduction catalysts.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Publisher: American Chemical Society
ISSN: 1932-7447
Funders: UK Economic and Social Research Council
Date of First Compliant Deposit: 18 August 2020
Date of Acceptance: 22 June 2020
Last Modified: 01 Oct 2020 11:24
URI: http://orca.cf.ac.uk/id/eprint/134271

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