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Title: Preparation and Characterization of Monodispersed WO3 Nanoclusters on TiO2(110)

Abstract

A procedure is described for preparing a novel model early transition metal oxide system for catalysis studies?direct sublimation of tungsten trioxide on TiO2(110). Isolated monodispersed cyclic trimers, i.e., (WO3)3, can be formed on TiO2(110) that are thermally stable up to at least 750 K. Although not readily generalizable to monodispersed (WO3)x clusters other than cyclic trimers, this protocol provides an ideal nanocluster platform for carrying out model system catalysis studies over a wide temperature range.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
898090
Report Number(s):
PNNL-SA-50486
8195; KC0301020; TRN: US200705%%404
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Catalysis Today, 120(2):186-195
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; TUNGSTEN OXIDES; SUBLIMATION; SUBSTRATES; TITANIUM OXIDES; NANOSTRUCTURES; CATALYSIS; Environmental Molecular Sciences Laboratory

Citation Formats

Kim, Jooho, Bondarchuk, Olexsandr, Kay, Bruce D., White, J. M., and Dohnalek, Zdenek. Preparation and Characterization of Monodispersed WO3 Nanoclusters on TiO2(110). United States: N. p., 2007. Web. doi:10.1016/j.cattod.2006.07.050.
Kim, Jooho, Bondarchuk, Olexsandr, Kay, Bruce D., White, J. M., & Dohnalek, Zdenek. Preparation and Characterization of Monodispersed WO3 Nanoclusters on TiO2(110). United States. doi:10.1016/j.cattod.2006.07.050.
Kim, Jooho, Bondarchuk, Olexsandr, Kay, Bruce D., White, J. M., and Dohnalek, Zdenek. Thu . "Preparation and Characterization of Monodispersed WO3 Nanoclusters on TiO2(110)". United States. doi:10.1016/j.cattod.2006.07.050.
@article{osti_898090,
title = {Preparation and Characterization of Monodispersed WO3 Nanoclusters on TiO2(110)},
author = {Kim, Jooho and Bondarchuk, Olexsandr and Kay, Bruce D. and White, J. M. and Dohnalek, Zdenek},
abstractNote = {A procedure is described for preparing a novel model early transition metal oxide system for catalysis studies?direct sublimation of tungsten trioxide on TiO2(110). Isolated monodispersed cyclic trimers, i.e., (WO3)3, can be formed on TiO2(110) that are thermally stable up to at least 750 K. Although not readily generalizable to monodispersed (WO3)x clusters other than cyclic trimers, this protocol provides an ideal nanocluster platform for carrying out model system catalysis studies over a wide temperature range.},
doi = {10.1016/j.cattod.2006.07.050},
journal = {Catalysis Today, 120(2):186-195},
number = ,
volume = ,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • Monodispersed supported clusters of catalytically important materials provide an excellent platform for model catalytic studies. Ultimately such systems can provide the detailed understanding of the site specific reactivity and yield the structure-reactivity relationships that cannot be obtained otherwise. Unfortunately preparation of such model systems requires highly complex experimental apparatus and has been achieved only for limited number of clusters, primarily those of metals.[1] Our work in this area focuses on supported transition-metal oxide catalysts which are of particular technological importance and have broad applications in partial oxidation of alcohols, oxidative dehydrogenation of hydrocarbons, and selective reduction of nitric oxide
  • Polymerization of formaldehyde, H2CO, was studied under ultrahigh vacuum conditions on a model catalyst consisting of monodispersed (WO3)3 clusters anchored on TiO2(110. Formaldehyde oligomers, (H2CO)n, desorbing from the polymer that formed on the catalyst surface are detected between 250 and 325 K in temperature programmed desorption experiments. At least two monolayers (ML) of H2CO are required on the surface to observe (H2CO)n desorption and the amount saturates for H2CO coverages in excess of ~30 ML. The presence of H2CO multilayers is required for the polymerization to take place indicating that it had to occur below 100 K. The saturation amountmore » increases with increasing coverage of (WO3)3 clusters with the highest amount of ~13 ML observed on 1.2 (WO3)3/nm2 . No (H2CO)n desorption was observed on the bare TiO2(110) surface.« less
  • A comparative study was conducted on the interaction of Pt with the (1x1) and (1x2) surface phases of rutile TiO{sub 2}(110). It was found that the surface structure and stoichiometry of TiO{sub 2} have profound effects on the formation and growth of nano-sized Pt clusters on TiO{sub 2}(110). On the (1x1) surface, Pt formed randomly-distributed, three-dimensional nanoclusters that coalesced and were encapsulated when thermally annealed. In contrast, smaller Pt clusters were identified to adsorb on top of the titanium atomic rows on the (1x2) surface and exhibited higher thermal stability. The stronger interaction observed for the Pt on the (1x2)more » surface is due to a charge transfer from Ti to Pt atoms. Vicinal TiO{sub 2}(110) surfaces with alternating (1x1) and (1x2) domains were used to verify the different interactions of Pt for the two domains. Upon Pt deposition, an array of self-organized Pt nanoclusters was formed on this surface. The self-organization is due to different interactions of Pt with the two different surface domains and preferential diffusion of Pt nanoclusters along the titanium atomic rows on the (1x2) surface.« less
  • Abstract not provided.