Synthesis And Characterization of Pt Clusters in Aqueous Solutions
Extended X-ray absorption fine structure (EXAFS) and UV-visible (UV-vis) spectroscopies were used to monitor the various steps involved in the synthesis of unprotected and poly(vinyl alcohol) (PVA)-protected aqueous colloidal Pt suspensions. The results indicate that on hydrolysis of the H{sub 2}PtCl{sub 6} precursor, the Cl{sup -} ligands were partially replaced by aquo ligands in the first coordination shell of Pt to form [PtCl{sub 2}(H{sub 2}O){sub 4}]{sup 2+}. Treatment of these species with NaBH{sub 4} under controlled pH conditions led to the formation of nearly uniform Pt{sub 4} and Pt{sub 6} clusters in the absence and presence of PVA, respectively. These highly dispersed colloidal Pt suspensions were stable for several months. The addition of 2-propanol (IPA) to both types of Pt suspensions led to some sintering of the Pt clusters, although both suspensions retained their colloidal nature. Less sintering was evident in the PVA-protected Pt suspension. Both the unprotected and the PVA-protected colloidal Pt suspensions were catalytically active for the liquid-phase selective oxidation of 2-propanol to acetone, with the unprotected suspension exhibiting the highest activity.
- Research Organization:
- Stanford Linear Accelerator Center (SLAC)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76SF00515
- OSTI ID:
- 953564
- Report Number(s):
- SLAC-REPRINT-2009-319
- Journal Information:
- J. Cat. 257:5,2008, Journal Name: J. Cat. 257:5,2008 Journal Issue: 1 Vol. 257; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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