Controlled surface modification of supported platinum group metal catalysts
Controlled surface modification of supported platinum group metal catalysts
The development of proton exchange membrane fuel cell (PEMFC) technologies relies upon many catalytic processes. The ability to specifically modify the surface of a catalyst with a secondary metal is beneficial as it could lead to increased performance and improved mechanistic knowledge.
Co and Cr surface modified Pt/C catalysts have been prepared by the controlled surface reaction between the reduced Pt surface and an organometallic precursor of the secondary metal. It was found, using X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) that the secondary metal was targeting the Pt surface sites, but that additional heat treatments were required to form an alloy. Oxygen reduction testing using a rotating disk electrode (RDE) demonstrated that the Pt3M alloy phase was required for the catalysts to exhibit a 2 to 3 fold enhancement towards the ORR. No enhancement was observed when the secondary metal was present at the surface of the catalyst in an unalloyed state. Pt modified Pd/C catalysts were prepared to reduce the Pt metal content whilst retaining its catalytic activity towards the oxygen reduction reaction (ORR). The Pt mass activities of the Pt/Pd/C catalysts towards the ORR were less than the 40 wt% Pt/C catalyst used as a comparison. It is believed that a larger Pd core particle is required to achieve improved Pt mass activities.
CeOx/Pt/Al2O3 catalysts were prepared for the water gas shift reaction and offered improved performance in comparison to Pt/Al2O3, but less than Pt/CeO2. X-ray absorption near edge spectroscopy (XANES) was used to confirm that Pt facilitated the reduction of Ce(IV) to Ce(III) in atmospheres of air, H2 and CO. It is proposed that the increase in activity observed on increasing the CeOx loading is consistent with the formate mechanism
University of Southampton
Wells, Peter Philip
de6ea53c-ced1-418a-ac33-3b29a063073a
2007
Wells, Peter Philip
de6ea53c-ced1-418a-ac33-3b29a063073a
Wells, Peter Philip
(2007)
Controlled surface modification of supported platinum group metal catalysts.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The development of proton exchange membrane fuel cell (PEMFC) technologies relies upon many catalytic processes. The ability to specifically modify the surface of a catalyst with a secondary metal is beneficial as it could lead to increased performance and improved mechanistic knowledge.
Co and Cr surface modified Pt/C catalysts have been prepared by the controlled surface reaction between the reduced Pt surface and an organometallic precursor of the secondary metal. It was found, using X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) that the secondary metal was targeting the Pt surface sites, but that additional heat treatments were required to form an alloy. Oxygen reduction testing using a rotating disk electrode (RDE) demonstrated that the Pt3M alloy phase was required for the catalysts to exhibit a 2 to 3 fold enhancement towards the ORR. No enhancement was observed when the secondary metal was present at the surface of the catalyst in an unalloyed state. Pt modified Pd/C catalysts were prepared to reduce the Pt metal content whilst retaining its catalytic activity towards the oxygen reduction reaction (ORR). The Pt mass activities of the Pt/Pd/C catalysts towards the ORR were less than the 40 wt% Pt/C catalyst used as a comparison. It is believed that a larger Pd core particle is required to achieve improved Pt mass activities.
CeOx/Pt/Al2O3 catalysts were prepared for the water gas shift reaction and offered improved performance in comparison to Pt/Al2O3, but less than Pt/CeO2. X-ray absorption near edge spectroscopy (XANES) was used to confirm that Pt facilitated the reduction of Ce(IV) to Ce(III) in atmospheres of air, H2 and CO. It is proposed that the increase in activity observed on increasing the CeOx loading is consistent with the formate mechanism
Text
1065213.pdf
- Version of Record
More information
Published date: 2007
Identifiers
Local EPrints ID: 466181
URI: http://eprints.soton.ac.uk/id/eprint/466181
PURE UUID: 8f58428c-dc11-4a59-b2a7-e7ae5e5da234
Catalogue record
Date deposited: 05 Jul 2022 04:40
Last modified: 16 Mar 2024 20:33
Export record
Contributors
Author:
Peter Philip Wells
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics