Alloying and Oxidation of PdAu Thin Films
Edström, Helen LU ; Gustafson, Johan LU ; Hagman, Benjamin LU ; von Allmen, Kim LU
; Carlsson, Per-Anders
; Schaefer, Andreas
and Jacobse, Leon
(2024)
In Thin Solid Films
790.
- Abstract
- The relation between catalytic activity and the presence of oxides on the catalyst’s surface has proven very complex, especially in the case of methane oxidation over Pd. While the metallic Pd surface and a thin, but at least two atomic layers thick, oxide film has been found catalytically active, a single-layer surface oxide or a too thick oxide film are both low-active. Unfortunately, under reaction conditions, the oxide tends to grow thick and deactivate. The reason for this deactivation is believed to be exposure of the PdO(100) surface, which does not have any suitable active sites for the methane adsorption and activation, in contrast to PdO(101), which is exposed for thin films. In an attempt to limit the thickness of the oxide... (More)
- The relation between catalytic activity and the presence of oxides on the catalyst’s surface has proven very complex, especially in the case of methane oxidation over Pd. While the metallic Pd surface and a thin, but at least two atomic layers thick, oxide film has been found catalytically active, a single-layer surface oxide or a too thick oxide film are both low-active. Unfortunately, under reaction conditions, the oxide tends to grow thick and deactivate. The reason for this deactivation is believed to be exposure of the PdO(100) surface, which does not have any suitable active sites for the methane adsorption and activation, in contrast to PdO(101), which is exposed for thin films. In an attempt to limit the thickness of the oxide film, and hence stabilise the active PdO orientation, we have investigated the oxidation of thin PdAu films. The effects of different mixtures (25%, 50%, and 75% Au, respectively) and treatments on the oxidation and orientation of the alloy and oxide films were investigated. As intended, PdAu turned out to be significantly more difficult to oxidise compared to pure Pd. This effect was even stronger than expected. Depending on the amount of Au present in the alloy, the orientation of the oxide is affected. At lower Au concentration, the desired (101) oxide orientation is favoured, while higher Au concentration favours the low-active (100) oxide orientation. Thus, PdAu might be a good candidate for methane oxidation if the Au concentration is low, probably below 25%. The larger lattice constant of Au compared to Pd might also affect the oxide orientation, so another choice of alloying material, e.g. PdPt, may also work to stabilise PdO(101). (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/e4e89ff3-99e6-4ef8-a8aa-dc9409cec864
- author
- Edström, Helen
LU
; Gustafson, Johan
LU
; Hagman, Benjamin
LU
; von Allmen, Kim
LU
; Carlsson, Per-Anders
; Schaefer, Andreas
and Jacobse, Leon
- organization
- publishing date
- 2024-01-09
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- alloying, bimetallic system, Grazing incidence X-ray diffraction, oxidation, Oxide formation, palladium-gold, thin film sample
- in
- Thin Solid Films
- volume
- 790
- article number
- 140212
- pages
- 11 pages
- publisher
- Elsevier
- external identifiers
-
- scopus:85181945730
- ISSN
- 0040-6090
- DOI
- 10.2139/ssrn.4600339
- language
- English
- LU publication?
- yes
- id
- e4e89ff3-99e6-4ef8-a8aa-dc9409cec864
- date added to LUP
- 2023-10-25 15:38:42
- date last changed
- 2024-02-07 12:27:54
@article{e4e89ff3-99e6-4ef8-a8aa-dc9409cec864,
abstract = {{The relation between catalytic activity and the presence of oxides on the catalyst’s surface has proven very complex, especially in the case of methane oxidation over Pd. While the metallic Pd surface and a thin, but at least two atomic layers thick, oxide film has been found catalytically active, a single-layer surface oxide or a too thick oxide film are both low-active. Unfortunately, under reaction conditions, the oxide tends to grow thick and deactivate. The reason for this deactivation is believed to be exposure of the PdO(100) surface, which does not have any suitable active sites for the methane adsorption and activation, in contrast to PdO(101), which is exposed for thin films. In an attempt to limit the thickness of the oxide film, and hence stabilise the active PdO orientation, we have investigated the oxidation of thin PdAu films. The effects of different mixtures (25%, 50%, and 75% Au, respectively) and treatments on the oxidation and orientation of the alloy and oxide films were investigated. As intended, PdAu turned out to be significantly more difficult to oxidise compared to pure Pd. This effect was even stronger than expected. Depending on the amount of Au present in the alloy, the orientation of the oxide is affected. At lower Au concentration, the desired (101) oxide orientation is favoured, while higher Au concentration favours the low-active (100) oxide orientation. Thus, PdAu might be a good candidate for methane oxidation if the Au concentration is low, probably below 25%. The larger lattice constant of Au compared to Pd might also affect the oxide orientation, so another choice of alloying material, e.g. PdPt, may also work to stabilise PdO(101).}},
author = {{Edström, Helen and Gustafson, Johan and Hagman, Benjamin and von Allmen, Kim and Carlsson, Per-Anders and Schaefer, Andreas and Jacobse, Leon}},
issn = {{0040-6090}},
keywords = {{alloying; bimetallic system; Grazing incidence X-ray diffraction; oxidation; Oxide formation; palladium-gold; thin film sample}},
language = {{eng}},
month = {{01}},
publisher = {{Elsevier}},
series = {{Thin Solid Films}},
title = {{Alloying and Oxidation of PdAu Thin Films}},
url = {{http://dx.doi.org/10.2139/ssrn.4600339}},
doi = {{10.2139/ssrn.4600339}},
volume = {{790}},
year = {{2024}},
}