| Attributs | Valeurs |
|---|
| type
| |
| Is Part Of
| |
| Subject
| |
| Title
| - EXAFS/XANES, XRD, and UV−Vis Characterization of Intrazeolitic Gold(I) Prepared byMonolayer Dispersion of AuCl3 inside Na−Y Zeolite
|
| has manifestation of work
| |
| related by
| |
| Author
| |
| Abstract
| - Preparations of AuCln in Na−Y zeolitewere characterized by means of X-ray diffraction (XRD),ultravioletdiffuse reflectance (UV−vis), Au LIII-edge X-rayabsorption near-edge structure (XANES), and extendedX-ray absorption fine structure (EXAFS).Au2Cl6 was first homogeneouslydispersed on the zeolite surfaceby mechanical mixing at room temperature under a nitrogen atmosphere.The thermal evacuation of themixed sample at 323 K for 72 h led to the eruption of a soleAu2Cl6 crystalline line at 2θ =14.70° due tothe condensation of the gold species on the zeolite surface. Thedetected Au−O bond by the EXAFS techniquehas a coordination distance of 2.16 Å, which is about the same as thatregistered for the tetrameric moleculeof dimethylgold(III) hydroxyl. Ramping theAu2Cl6−Na−Y reaction temperature to338 K yielded appreciableamounts of Au(I) ions which were embedded with theCl- ions in a (AuCl)n zig-zag-likestructure. TheAu−O interactions were not apparent due to the removal of OH attachedto Au(III) at 338 K, thereby causingthe partial reduction of Au(III) to Au(I). In agreementwith the EXAFS data, the intensity of thresholdresonance due to the unoccupied d-states in the XANES spectrum of thepreparation at 323 K declined followingan increase of the temperature to 338 K, to resemble that recorded forthe AuCl reference compound. Thisobservation was associated with the UV−vis band broadening andshifting at 225 nm to the lower energyside because of the increase in population of the bridged Au−Cllinkages over the terminal ones.
|
| article type
| |
| is part of this journal
| |
