Effect of supporting surface layers on catalytic activities of gold nanoparticles in CO oxidation

Wenfu Yan; Shannon M. Mahurin; Bei Chen; Steven H. Overbury; Sheng Dai

doi:10.1021/jp052006m

Effect of supporting surface layers on catalytic activities of gold nanoparticles in CO oxidation

Wenfu Yan, Shannon M. Mahurin, Bei Chen, Steven H. Overbury, Sheng Dai

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Abstract

The surfaces of fumed silica materials were modified with a surface sol-gel process for catalysis applications. This surface-modification approach allows not only a monolayer growth of TiO ₂ or Al ₂O ₃ but also a stepwise double-layer growth of TiO ₂/TiO ₂, Al ₂O ₃/Al ₂O ₃, TiO ₂/Al ₂O ₃, or Al ₂O ₃/TiO ₂ on the surfaces of the silica materials with a monolayer precision. XRD analyses revealed that the coated monolayers and double layers of TiO ₂ and Al ₂O ₃ were amorphous. Gold nanoparticles were successfully deposited on the above six surface-modified silica materials via a deposition-precipitation method. The catalytic activities of these six gold catalysts for CO oxidation are highly dependent on the structures of their surface monolayers or double layers. The gold catalyst supported on the silica material functionalized with a TiO ₂ monolayer (Au/TiO ₂) is the most active in both as-synthesized and oxidized forms, while the gold catalyst supported on the silica material functionalized with an Al ₂O ₃/TiO ₂ double layer (Au/Al2O ₃/TiO ₂/SiO ₂) is the most active in the reduced form among the six catalysts. Surprisingly, the gold catalyst supported on the silica material functionalized with a TiO ₂/Al ₂O ₃ double layer (Au/TiO ₂/Al ₂O ₃/SiO ₂) has much less activity than Au/Al ₂O ₃/TiO ₂/SiO ₂ under all various treatments, underscoring the sensitivity of the catalytic activity to the structure of the supporting surfaces.

Original language	English
Pages (from-to)	15489-15496
Number of pages	8
Journal	Journal of Physical Chemistry B
Volume	109
Issue number	32
DOIs	https://doi.org/10.1021/jp052006m
State	Published - Aug 18 2005

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@article{88c1219c70794567a5636b5922ae24f8,

title = "Effect of supporting surface layers on catalytic activities of gold nanoparticles in CO oxidation",

abstract = "The surfaces of fumed silica materials were modified with a surface sol-gel process for catalysis applications. This surface-modification approach allows not only a monolayer growth of TiO 2 or Al 2O 3 but also a stepwise double-layer growth of TiO 2/TiO 2, Al 2O 3/Al 2O 3, TiO 2/Al 2O 3, or Al 2O 3/TiO 2 on the surfaces of the silica materials with a monolayer precision. XRD analyses revealed that the coated monolayers and double layers of TiO 2 and Al 2O 3 were amorphous. Gold nanoparticles were successfully deposited on the above six surface-modified silica materials via a deposition-precipitation method. The catalytic activities of these six gold catalysts for CO oxidation are highly dependent on the structures of their surface monolayers or double layers. The gold catalyst supported on the silica material functionalized with a TiO 2 monolayer (Au/TiO 2) is the most active in both as-synthesized and oxidized forms, while the gold catalyst supported on the silica material functionalized with an Al 2O 3/TiO 2 double layer (Au/Al2O 3/TiO 2/SiO 2) is the most active in the reduced form among the six catalysts. Surprisingly, the gold catalyst supported on the silica material functionalized with a TiO 2/Al 2O 3 double layer (Au/TiO 2/Al 2O 3/SiO 2) has much less activity than Au/Al 2O 3/TiO 2/SiO 2 under all various treatments, underscoring the sensitivity of the catalytic activity to the structure of the supporting surfaces.",

author = "Wenfu Yan and Mahurin, {Shannon M.} and Bei Chen and Overbury, {Steven H.} and Sheng Dai",

year = "2005",

month = aug,

day = "18",

doi = "10.1021/jp052006m",

language = "English",

volume = "109",

pages = "15489--15496",

journal = "Journal of Physical Chemistry B",

issn = "1520-6106",

publisher = "American Chemical Society",

number = "32",

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T1 - Effect of supporting surface layers on catalytic activities of gold nanoparticles in CO oxidation

AU - Yan, Wenfu

AU - Mahurin, Shannon M.

AU - Chen, Bei

AU - Overbury, Steven H.

AU - Dai, Sheng

PY - 2005/8/18

Y1 - 2005/8/18

N2 - The surfaces of fumed silica materials were modified with a surface sol-gel process for catalysis applications. This surface-modification approach allows not only a monolayer growth of TiO 2 or Al 2O 3 but also a stepwise double-layer growth of TiO 2/TiO 2, Al 2O 3/Al 2O 3, TiO 2/Al 2O 3, or Al 2O 3/TiO 2 on the surfaces of the silica materials with a monolayer precision. XRD analyses revealed that the coated monolayers and double layers of TiO 2 and Al 2O 3 were amorphous. Gold nanoparticles were successfully deposited on the above six surface-modified silica materials via a deposition-precipitation method. The catalytic activities of these six gold catalysts for CO oxidation are highly dependent on the structures of their surface monolayers or double layers. The gold catalyst supported on the silica material functionalized with a TiO 2 monolayer (Au/TiO 2) is the most active in both as-synthesized and oxidized forms, while the gold catalyst supported on the silica material functionalized with an Al 2O 3/TiO 2 double layer (Au/Al2O 3/TiO 2/SiO 2) is the most active in the reduced form among the six catalysts. Surprisingly, the gold catalyst supported on the silica material functionalized with a TiO 2/Al 2O 3 double layer (Au/TiO 2/Al 2O 3/SiO 2) has much less activity than Au/Al 2O 3/TiO 2/SiO 2 under all various treatments, underscoring the sensitivity of the catalytic activity to the structure of the supporting surfaces.

AB - The surfaces of fumed silica materials were modified with a surface sol-gel process for catalysis applications. This surface-modification approach allows not only a monolayer growth of TiO 2 or Al 2O 3 but also a stepwise double-layer growth of TiO 2/TiO 2, Al 2O 3/Al 2O 3, TiO 2/Al 2O 3, or Al 2O 3/TiO 2 on the surfaces of the silica materials with a monolayer precision. XRD analyses revealed that the coated monolayers and double layers of TiO 2 and Al 2O 3 were amorphous. Gold nanoparticles were successfully deposited on the above six surface-modified silica materials via a deposition-precipitation method. The catalytic activities of these six gold catalysts for CO oxidation are highly dependent on the structures of their surface monolayers or double layers. The gold catalyst supported on the silica material functionalized with a TiO 2 monolayer (Au/TiO 2) is the most active in both as-synthesized and oxidized forms, while the gold catalyst supported on the silica material functionalized with an Al 2O 3/TiO 2 double layer (Au/Al2O 3/TiO 2/SiO 2) is the most active in the reduced form among the six catalysts. Surprisingly, the gold catalyst supported on the silica material functionalized with a TiO 2/Al 2O 3 double layer (Au/TiO 2/Al 2O 3/SiO 2) has much less activity than Au/Al 2O 3/TiO 2/SiO 2 under all various treatments, underscoring the sensitivity of the catalytic activity to the structure of the supporting surfaces.

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JF - Journal of Physical Chemistry B

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Effect of supporting surface layers on catalytic activities of gold nanoparticles in CO oxidation

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