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Hydrogen oxidation kinetics on platinum-palladium bimetallic thin films for solid acid fuel cells

Paik, Haemin and Berenov, Andrey V. and Skinner, Stephen J. and Haile, Sossina M. (2019) Hydrogen oxidation kinetics on platinum-palladium bimetallic thin films for solid acid fuel cells. APL Materials, 7 (1). Art. No. 013201. ISSN 2166-532X. https://resolver.caltech.edu/CaltechAUTHORS:20181206-144519037

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Abstract

Solid acid fuel cells (SAFCs) based on the proton-conductive electrolyte CsH2PO4 have shown promising power densities at an intermediate operating temperature of ∼250 °C. However, Pt loadings in SAFCs remain higher than desirable, and the electrocatalysis mechanisms in these devices are still unknown. Here, hydrogen oxidation kinetics on Pt and Pt-Pd bimetallic thin film electrodes on CsH2PO4 have been evaluated to establish the potential for a beneficial role of Pd in SAFC anodes. Symmetric cells fabricated by depositing a metal film on both sides of electrolyte discs are characterized for studying hydrogen electro-oxidation across the gas|metal|CsH2PO4 structure. It was found that Pd reacts with CsH2PO4, forming palladium phosphide at the metal-electrolyte interface. Accordingly, the activity of Pd was examined in a bilayer geometry of Pd|Pt|CsH2PO4|Pt|Pd. The bilayer Pt|Pd films showed much higher activity for hydrogen electro-oxidation than films of Pt alone, as measured by AC impedance spectroscopy. Ex situ low energy ion scattering and scanning transmission electron microscopy revealed that Pd diffused into the Pt layer under operating conditions. The dramatic impact of Pd along with its presence throughout the film suggests that it catalyzes reactions at both the metal-gas and metal-electrolyte interfaces, as well as increasing hydrogen diffusion rates through the films.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1063/1.5050093DOIArticle
ORCID:
AuthorORCID
Skinner, Stephen J.0000-0001-5446-2647
Haile, Sossina M.0000-0002-5293-6252
Additional Information:© Author(s) 2018. All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Submitted: 27 July 2018 • Accepted: 2 September 2018 • Published Online: 6 December 2018. This research was supported by the Kwanjeong Educational Foundation and the U.S. Department of Energy, through ARPA-e Contract Nos. DE-AR0000495 and DE-AR0000813. This work utilized Micro/Nano Fabrication Facility (NUFAB), NUANCE Center (EPIC and Keck-II), and J. B. Cohen Diffraction X-ray Diffraction Facility at Northwestern University, which are all supported by the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (No. NSF ECCS-1542205) and MRSEC program of the National Science Foundation (No. DMR-1720139) at the Materials Research Center. We thank Xin Xu and Kaiting Li for assistance with sample preparation.
Funders:
Funding AgencyGrant Number
Kwanjeong Educational FoundationUNSPECIFIED
Department of Energy (DOE)DE-AR0000495
Department of Energy (DOE)DE-AR0000813
NSFECCS-1542205
NSFDMR-1720139
Issue or Number:1
Record Number:CaltechAUTHORS:20181206-144519037
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20181206-144519037
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91538
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:06 Dec 2018 22:55
Last Modified:03 Oct 2019 20:35

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