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Title: EPR investigation of the nature of oxygen species present on the surface of gold impregnated cerium oxide
Authors: Aboukaïs, Antoine
Aouad, Samer 
Skaf, Mira
Hany, Sara
Labaki, Madona
Cousin, Renaud
Abi Aad, Edmond
Affiliations: Department of Chemistry 
Keywords: Electron paramagnetic resonance (EPR)
Surface properties
Issue Date: 2016
Part of: Journal of materials chemistry and physics
Volume: 170
Start page: 285
End page: 293
The electron paramagnetic resonance (EPR) spectroscopy was used to study the adsorption of air at room temperature on Au/CeO2 solids prepared by impregnating gold on cerium oxide. Two EPR signals, P and M, where then identified. The P signal having g//>g⊥, was mainly present on the EPR spectra recorded at room temperature and −196 °C for solids with low gold content (Au less than 1.25 wt.%). This signal was attributed to O2− species strongly attached to the CeO2 surface. The M signal with g⊥ > g// was only observed at −196 °C. Both P and M signals were obtained for solids with low gold content while M alone was present for solids with high gold content (2.5 wt.% and above). The M signal was also obtained even when air was adsorbed at −196 °C on the solids. 17O-enriched molecular oxygen adsorption allowed the identification of the M signal as being the result of O2− species. These species are weakly interacting with the surface of ceria containing Cl− ions probably present in CeOCl micro-phase. The O2− species responsible of the P signal are formed in solids containing gold nanoparticles and are efficient in the catalytic total oxidation of propylene.
DOI: 10.1016/j.matchemphys.2015.12.053
Ezproxy URL: Link to full text
Type: Journal Article
Appears in Collections:Department of Chemistry

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