Issue 32, 2012

Model oxide-supported metal catalysts – comparison of ultrahigh vacuum and solution based preparation of Pd nanoparticles on a single-crystalline oxide substrate

Abstract

Using single-crystalline Fe3O4(111) films grown over Pt(111) in UHV as a model-support, we have characterized the nucleation behaviour and chemical properties of Pd particles grown over the film using different deposition techniques with scanning tunnelling microscopy and X-ray photoelectron spectroscopy. Comparison of Pd/Fe3O4 samples created via Pd evaporation under UHV conditions and those resulting from the solution deposition of Pd-hydroxo complexes reveals that changes in the interfacial functionalization of such samples (i.e. roughening and hydroxylation) govern the differences in Pd nucleation behavior observed over pristine oxides relative to those exposed to alkaline solutions. Furthermore, it appears that other differences in the nature of the Pd precursor state (i.e. gas-phase Pd in UHV vs. [Pd(OH)2]n aqueous complexes) play a negligible role in Pd nucleation and growth behaviour at elevated temperatures in UHV, suggesting facile decomposition of the Pd complexes deposited from the liquid phase. Applying temperature programmed desorption and infrared spectroscopy to probe the CO chemisorption properties of such samples after reduction in different reagents (CO, H2) shows the formation of bimetallic PdFe alloys following reduction in H2, but monometallic Pd particles after CO reduction.

Graphical abstract: Model oxide-supported metal catalysts – comparison of ultrahigh vacuum and solution based preparation of Pd nanoparticles on a single-crystalline oxide substrate

Article information

Article type
Paper
Submitted
07 May 2012
Accepted
02 Jul 2012
First published
02 Jul 2012

Phys. Chem. Chem. Phys., 2012,14, 11525-11533

Model oxide-supported metal catalysts – comparison of ultrahigh vacuum and solution based preparation of Pd nanoparticles on a single-crystalline oxide substrate

H. Wang, W. E. Kaden, R. Dowler, M. Sterrer and H. Freund, Phys. Chem. Chem. Phys., 2012, 14, 11525 DOI: 10.1039/C2CP41459G

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