Oxidation of palladium on Au(111) and ZnO(0001) supports
- Univ. of South Florida, Tampa, FL (United States). Dept. of Physics
- Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials
The oxidation of supported Pd-deposits on Au(111) and ZnO(0001) single crystals has been studied by x- ray photoemission spectroscopy (XPS). Oxidation has been carried out ex-situ in a high-pressure cell with subsequent vacuum-transfer and characterization by XPS in ultrahigh vacuum (UHV), as well as using in-situ characterization by synchrotron based near-ambient pressure XPS. On Au(111) alloying of Pd with the substrate competes with oxidation and only sufficiently thick Pd films have been found to oxidize. For Pd on ZnO the oxidation conditions depend on the amount of deposited Pd. Thicker Pd deposits behave similar to bulk Pd, while thinner films oxidize already at lower temperatures. Interestingly, for very small amounts of Pd, in-situ XPS shows full oxidation at room temperature and at less than 0.6 mbar O₂ pressure. This indicates a lowering of the kinetic barriers for oxidation of very small supported Pd-clusters. The formed oxide is, however, not stable in UHV and a slow reduction is observed. The instability of this oxide indicates that the Pd-oxide formed at the interface to ZnO may have different chemical properties compared to bulk PdO or surface oxides on Pd.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC00112704; AC02-98CH10886; FG02-09ER1608
- OSTI ID:
- 1182507
- Alternate ID(s):
- OSTI ID: 1224232
- Report Number(s):
- BNL-107469-2015-JA; JCPSA6; R&D Project: 16080/16080; KC0403020; TRN: US1500506
- Journal Information:
- Journal of Chemical Physics, Vol. 141, Issue 15; ISSN 0021-9606
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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