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Title: Oxidation of palladium on Au(111) and ZnO(0001) supports

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.
 [1] ;  [2] ;  [1] ;  [2] ;  [1]
  1. Univ. of South Florida, Tampa, FL (United States). Dept. of Physics
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials
Publication Date:
Report Number(s):
Journal ID: ISSN 0021-9606; JCPSA6; R&D Project: 16080/16080; KC0403020; TRN: US1500506
Grant/Contract Number:
SC00112704; AC02-98CH10886; FG02-09ER1608
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 141; Journal Issue: 15; Journal ID: ISSN 0021-9606
American Institute of Physics (AIP)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; X-ray photoelectron spectroscopy; oxide surfaces; surface oxidation; gold; x-ray photoemission spectroscopy; palladium catalysts
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1224232