Surface and bulk characterization of Rh/ZrO{sub 2} prepared by absorption of Rh{sub 4}(CO){sub 12} clusters on ZrO{sub 2} powder

Journal Article · Thu May 01 04:00:00 EDT 1997 · Journal of Materials Research

DOI:https://doi.org/10.1557/JMR.1997.0187· OSTI ID:508971

Depero, L E ^[1]; Bertoncello, R ^[2]; Boni, T ^[3]; Levrangi, P; Sora, I N; Tempesti, E ^[1]; Parmigiani, F ^[4]

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1. INFM and Department of Materials Chemistry and Physics, University of Brescia, Brescia (Italy)
2. Department of Inorganic, Metallorganic and Analytical Chemistry, University of Padua, Padua (Italy)
3. Department of Materials Science, CISE, S.p.A., Milano (Italy)
4. Department of Physics, Polytechnic of Milan, P.zza Leonardo da Vinci 32, 20133 Milan (Italy)

Rh nanoparticles supported on ZrO{sub 2} powder were prepared by adsorbing Rh{sub 4}(CO){sub 12} clusters from hexane solution under Ar atmosphere. Four samples with Rh content ranging from 0.25 Rh wt.{percent} up to 4.10 Rh wt.{percent} are studied by x-ray diffraction (XRD), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), scanning Auger microscopy (SAM), and time of flight secondary ion mass spectroscopy (ToF-SIMS). TEM measurements show, for all the samples, Rh particles with a size of about 50 {Angstrom}. The 4.10 Rh wt.{percent} sample show also some agglomerates of Rh nanoparticles and only for this sample Rh metallic phase was detected by XRD. The profile analysis of the XRD lines indicate an average size of the Rh crystallites of about 60 {Angstrom}. XPS studies show only a single spectral component for the Zr3d{sub 5/2} core line at 182.2 eV. Instead, at least, two components at 307.2 eV and 308.5 eV are detected for the Rh3d{sub 5/2} core line. These results suggest that Zr is present only as oxidized state, whereas nonoxidized and oxidized Rh are both observed. A nonoxidized Rh state is also suggested by the XPS valence band electron removal spectrum which exhibits a significant emission within the ZrO{sub 2} band gap assigned to Rh 4d bands. A further support to this finding arises from scanning Auger maps of O{sub KVV}, and Rh{sub M{sub 45}N{sub 23}V} where nonoxidized Rh is observed. Finally scanning Auger maps using the O{sub KVV} and the Zr{sub M{sub 45}N{sub 23}V} emissions show surface regions where only the Zr Auger lines are detected, whereas on pure ZrO{sub 2} powder this effect is not observed. Since it is possible to rule out from the XPS Zr3d core line spectra, the presence of metallic zirconium hydrogen spillover mechanisms are invoked to explain these results. {copyright} {ital 1997 Materials Research Society.}

• OSTI ID: 508971
• Journal Information: Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 5 Vol. 12; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADSORPTION
CARBONYLS
CATALYSTS
ELECTRONIC STRUCTURE
MOLECULAR CLUSTERS
PARTICLES
PHOTOELECTRON SPECTROSCOPY
POWDERS
RHODIUM
RHODIUM COMPOUNDS
SYNTHESIS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ZIRCONIUM OXIDES