Gold Nanoparticles on Ceria: Importance of O Vacancies in the Activation of Gold

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Topics in Catalysis

DOI:https://doi.org/10.1007/s11244-007-0280-1· OSTI ID:929928

Rodriguez, J; Wang, X; Liu, P; Wen, W; Hanson, J; Hrbek, J; Perez, M; Evans, J

Synchrotron-based techniques (high-resolution photoemission, in-situ X-ray absorption spectroscopy, and time-resolved X-ray diffraction) have been used to study the destruction of SO{sub 2} and the water-gas shift (WGS, CO + H{sub 2}O {yields} H{sub 2} + CO{sub 2}) reaction on a series of gold/ceria systems. The adsorption and chemistry of SO{sub 2} was investigated on Au/CeO{sub 2}(111) and AuO{sub x} /CeO{sub 2} surfaces. The heat of adsorption of the molecule on Au nanoparticles supported on stoichiometric CeO{sub 2}(111) was 4-7 kcal/mol larger than on Au(111). However, there was negligible dissociation of SO{sub 2} on the Au/CeO{sub 2}(111) surfaces. The full decomposition of SO{sub 2} was observed only after introducing O vacancies in the ceria support. AuO{sub x} /CeO{sub 2} surfaces were found to be much less chemically active than Au/CeO{sub 2}(111) or Au/CeO{sub 2-x} (111) surfaces. In a separate set of experiments, in-situ time-resolved X-ray diffraction and X-ray absorption spectroscopy were used to monitor the behavior of nanostructured (Au + AuO{sub x})-CeO{sub 2} catalysts under the WGS reaction. At temperatures above 250 C, a complete AuO{sub x} {yields} Au transformation was observed with high catalytic activity. Photoemission results for the oxidation and reduction of Au nanoparticles supported on rough ceria films or a CeO{sub 2}(111) single crystal corroborate that cationic Au{sup {delta}+} species cannot be the key sites responsible for the WGS activity at high temperatures. The active sites in (Au + AuO{sub x})/ceria catalysts should involve pure gold nanoparticles in contact with O vacancies of the oxide.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 929928
• Report Number(s): BNL--80522-2008-JA
• Journal Information: Topics in Catalysis, Journal Name: Topics in Catalysis Journal Issue: 39449 Vol. 44
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ADSORPTION HEAT
CATALYST SUPPORTS
CATALYTIC EFFECTS
CERIUM OXIDES
CHEMICAL ACTIVATION
DECOMPOSITION
GOLD
NANOSTRUCTURES
OXYGEN
SHIFT PROCESSES
SULFUR DIOXIDE
VACANCIES
WATER GAS
national synchrotron light source