Palladium catalysts synthesized by atomic layer deposition for methanol decomposition

Hao Feng, Jeffrey W. Elam, Joseph A. Libera, Worajit Setthapun, Peter C Stair

Research output: Contribution to journalArticle

94 Citations (Scopus)

Abstract

Atomic layer deposition (ALD) palladium films were deposited at 200 °C on various ALD metal oxide surfaces using sequential exposures to Pd(II) hexafluoroacetylacetonate (Pd(hfac)2) and formalin. In situ quartz crystal microbalance measurements as well as ex situ measurements performed on planar substrates revealed that the Pd growth begins with a relatively slow nucleation process and accelerates once an adequate amount of Pd has deposited on the surface. Furthermore, the Pd nucleation is faster on ALD ZnO surfaces compared to ALD Al2O3 surfaces. ALD was utilized to synthesize highly dispersed, uniform Pd nanoparticles (1 to 2 nm in diameter) on ALD ZnO and Al2O3 coated mesoporous silica gel, and the catalytic performances of these samples were compared in the methanol decomposition reaction. The ALD Pd-Al2O3 showed high activity and hydrogen selectivity at relatively low temperatures while the ALD Pd-ZnO showed very low activity as well as quick deactivation. In situ extended X-ray absorption fine structure (EXAFS) measurement revealed that the Pd supported on ZnO "dissolves" into the substrate during the methanol decomposition reaction which accounts for the gradual disappearance of its catalytic activity. By applying one cycle of ALD Al2O3 on top of the Pd-ZnO catalyst, the activity was enhanced and the catalyst deactivation was mitigated. This Al2O3 overcoating method stabilizes the Pd-ZnO and effectively prevents the dissolution of Pd into the ZnO substrate.

Original languageEnglish
Pages (from-to)3133-3142
Number of pages10
JournalChemistry of Materials
Volume22
Issue number10
DOIs
Publication statusPublished - May 25 2010

Fingerprint

Atomic layer deposition
Palladium
Methanol
Decomposition
Catalysts
Catalyst activity
Nucleation
Substrates
Catalyst deactivation
Quartz crystal microbalances
Silica Gel
X ray absorption
Silica gel
Formaldehyde
Oxides
Hydrogen
Dissolution
Metals
Nanoparticles

ASJC Scopus subject areas

  • Materials Chemistry
  • Chemical Engineering(all)
  • Chemistry(all)

Cite this

Palladium catalysts synthesized by atomic layer deposition for methanol decomposition. / Feng, Hao; Elam, Jeffrey W.; Libera, Joseph A.; Setthapun, Worajit; Stair, Peter C.

In: Chemistry of Materials, Vol. 22, No. 10, 25.05.2010, p. 3133-3142.

Research output: Contribution to journalArticle

Feng, Hao ; Elam, Jeffrey W. ; Libera, Joseph A. ; Setthapun, Worajit ; Stair, Peter C. / Palladium catalysts synthesized by atomic layer deposition for methanol decomposition. In: Chemistry of Materials. 2010 ; Vol. 22, No. 10. pp. 3133-3142.
@article{c569bfd16b0542c7b2dcd097ec2760a3,
title = "Palladium catalysts synthesized by atomic layer deposition for methanol decomposition",
abstract = "Atomic layer deposition (ALD) palladium films were deposited at 200 °C on various ALD metal oxide surfaces using sequential exposures to Pd(II) hexafluoroacetylacetonate (Pd(hfac)2) and formalin. In situ quartz crystal microbalance measurements as well as ex situ measurements performed on planar substrates revealed that the Pd growth begins with a relatively slow nucleation process and accelerates once an adequate amount of Pd has deposited on the surface. Furthermore, the Pd nucleation is faster on ALD ZnO surfaces compared to ALD Al2O3 surfaces. ALD was utilized to synthesize highly dispersed, uniform Pd nanoparticles (1 to 2 nm in diameter) on ALD ZnO and Al2O3 coated mesoporous silica gel, and the catalytic performances of these samples were compared in the methanol decomposition reaction. The ALD Pd-Al2O3 showed high activity and hydrogen selectivity at relatively low temperatures while the ALD Pd-ZnO showed very low activity as well as quick deactivation. In situ extended X-ray absorption fine structure (EXAFS) measurement revealed that the Pd supported on ZnO {"}dissolves{"} into the substrate during the methanol decomposition reaction which accounts for the gradual disappearance of its catalytic activity. By applying one cycle of ALD Al2O3 on top of the Pd-ZnO catalyst, the activity was enhanced and the catalyst deactivation was mitigated. This Al2O3 overcoating method stabilizes the Pd-ZnO and effectively prevents the dissolution of Pd into the ZnO substrate.",
author = "Hao Feng and Elam, {Jeffrey W.} and Libera, {Joseph A.} and Worajit Setthapun and Stair, {Peter C}",
year = "2010",
month = "5",
day = "25",
doi = "10.1021/cm100061n",
language = "English",
volume = "22",
pages = "3133--3142",
journal = "Chemistry of Materials",
issn = "0897-4756",
publisher = "American Chemical Society",
number = "10",

}

TY - JOUR

T1 - Palladium catalysts synthesized by atomic layer deposition for methanol decomposition

AU - Feng, Hao

AU - Elam, Jeffrey W.

AU - Libera, Joseph A.

AU - Setthapun, Worajit

AU - Stair, Peter C

PY - 2010/5/25

Y1 - 2010/5/25

N2 - Atomic layer deposition (ALD) palladium films were deposited at 200 °C on various ALD metal oxide surfaces using sequential exposures to Pd(II) hexafluoroacetylacetonate (Pd(hfac)2) and formalin. In situ quartz crystal microbalance measurements as well as ex situ measurements performed on planar substrates revealed that the Pd growth begins with a relatively slow nucleation process and accelerates once an adequate amount of Pd has deposited on the surface. Furthermore, the Pd nucleation is faster on ALD ZnO surfaces compared to ALD Al2O3 surfaces. ALD was utilized to synthesize highly dispersed, uniform Pd nanoparticles (1 to 2 nm in diameter) on ALD ZnO and Al2O3 coated mesoporous silica gel, and the catalytic performances of these samples were compared in the methanol decomposition reaction. The ALD Pd-Al2O3 showed high activity and hydrogen selectivity at relatively low temperatures while the ALD Pd-ZnO showed very low activity as well as quick deactivation. In situ extended X-ray absorption fine structure (EXAFS) measurement revealed that the Pd supported on ZnO "dissolves" into the substrate during the methanol decomposition reaction which accounts for the gradual disappearance of its catalytic activity. By applying one cycle of ALD Al2O3 on top of the Pd-ZnO catalyst, the activity was enhanced and the catalyst deactivation was mitigated. This Al2O3 overcoating method stabilizes the Pd-ZnO and effectively prevents the dissolution of Pd into the ZnO substrate.

AB - Atomic layer deposition (ALD) palladium films were deposited at 200 °C on various ALD metal oxide surfaces using sequential exposures to Pd(II) hexafluoroacetylacetonate (Pd(hfac)2) and formalin. In situ quartz crystal microbalance measurements as well as ex situ measurements performed on planar substrates revealed that the Pd growth begins with a relatively slow nucleation process and accelerates once an adequate amount of Pd has deposited on the surface. Furthermore, the Pd nucleation is faster on ALD ZnO surfaces compared to ALD Al2O3 surfaces. ALD was utilized to synthesize highly dispersed, uniform Pd nanoparticles (1 to 2 nm in diameter) on ALD ZnO and Al2O3 coated mesoporous silica gel, and the catalytic performances of these samples were compared in the methanol decomposition reaction. The ALD Pd-Al2O3 showed high activity and hydrogen selectivity at relatively low temperatures while the ALD Pd-ZnO showed very low activity as well as quick deactivation. In situ extended X-ray absorption fine structure (EXAFS) measurement revealed that the Pd supported on ZnO "dissolves" into the substrate during the methanol decomposition reaction which accounts for the gradual disappearance of its catalytic activity. By applying one cycle of ALD Al2O3 on top of the Pd-ZnO catalyst, the activity was enhanced and the catalyst deactivation was mitigated. This Al2O3 overcoating method stabilizes the Pd-ZnO and effectively prevents the dissolution of Pd into the ZnO substrate.

UR - http://www.scopus.com/inward/record.url?scp=77952525210&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77952525210&partnerID=8YFLogxK

U2 - 10.1021/cm100061n

DO - 10.1021/cm100061n

M3 - Article

AN - SCOPUS:77952525210

VL - 22

SP - 3133

EP - 3142

JO - Chemistry of Materials

JF - Chemistry of Materials

SN - 0897-4756

IS - 10

ER -