High catalytic activity of Au/CeOx/TiO₂(110) controlled by the nature of the mixed-metal oxide at the nanometer level

Mixed-metal oxides play a very important role in many areas of chemistry, physics, materials science, and geochemistry. Recently, there has been a strong interest in understanding phenomena associated with the deposition of oxide nanoparticles on the surface of a second (host) oxide. Here, scanning...

Full description

Saved in:
Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2009, Vol.106 (13), p.4975-4980
Main Authors: Park, Joon B, Graciani, Jesus, Evans, Jaime, Stacchiola, Dario, Ma, Shuguo, Liu, Ping, Nambu, Akira, Sanz, Javier Fernández, Hrbek, Jan, Rodriguez, José A
Format: Article
Language:English
Subjects:
carbon dioxide
carbon monoxide
catalysts
catalytic activity
cations
ceric oxide
cerium
geochemistry
gold
hydrogen
hydrogen production
nanogold
nanoparticles
oxidation
oxygen
physics
scanning tunneling microscopy
titanium dioxide
water
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Mixed-metal oxides play a very important role in many areas of chemistry, physics, materials science, and geochemistry. Recently, there has been a strong interest in understanding phenomena associated with the deposition of oxide nanoparticles on the surface of a second (host) oxide. Here, scanning tunneling microscopy, photoemission, and density-functional calculations are used to study the behavior of ceria nanoparticles deposited on a TiO₂(110) surface. The titania substrate imposes nontypical coordination modes on the ceria nanoparticles. In the CeOx/TiO₂(110) systems, the Ce cations adopt an structural geometry and an oxidation state (+3) that are quite different from those seen in bulk ceria or for ceria nanoparticles deposited on metal substrates. The increase in the stability of the Ce³⁺ oxidation state leads to an enhancement in the chemical and catalytic activity of the ceria nanoparticles. The codeposition of ceria and gold nanoparticles on a TiO₂(110) substrate generates catalysts with an extremely high activity for the production of hydrogen through the water-gas shift reaction (H₂O + CO [rightward arrow] H₂ + CO₂) or for the oxidation of carbon monoxide (2CO + O₂ [rightward arrow] 2CO₂). The enhanced stability of the Ce³⁺ state is an example of structural promotion in catalysis described here on the atomic level. The exploration of mixed-metal oxides at the nanometer level may open avenues for optimizing catalysts through stabilization of unconventional surface structures with special chemical activity.
ISSN:0027-8424
1091-6490