Abstract
Ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) have been used to study electronic properties and the surface structure of the TiO2(rutile)(110) surface and the Ni/TiO2(110) interface. A sputter-cleaned TiO2(110) surface shows a (1 × 1) LEED pattern after annealing at 400°C for 15 min and a (1 × 2) pattern after an extended annealing at 615°C. AES showed that the O(510 eV) Ti(380 eV) peak ratio change was within 5% for these two surfaces. From the binding energy shift of the Ni 2p 3 2 peak and the kinetic energy shift of the Ni L3M2,3M2,3 Auger peak as a function of Ni coverage, we measure a relaxation shift of 0.7 eV and a chemical shift of 0.75 eV of the Ni 2p 3 2 peak for bulk Ni relative to half a monolayer of deposited Ni on the TiO2(110)-(1 × 1) surface. These indicated that Ni atoms at the Ni/TiO2(110)-(1 × 1) interface are negatively charged and the amount of charge transferred is estimated to be 0.13 e- Ni atom. On the TiO2(110)-(1 × 2) surface, the amount of charge transfer is roughly 0.07 e- Ni atom. Such a variation in the charge state of Ni may affect the CO chemisorption and hence its methanation activity. Nickel deposited on the TiO2(110) surface diffuses into bulk TiO2 at 300°C or higher. Annealing at 300°C for 5 min results in a (1 × 2) LEED pattern, indicating long range ordering of the Ni overlay er on the TiO2(110) surface.
Original language | English (US) |
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Pages (from-to) | 1-14 |
Number of pages | 14 |
Journal | Surface Science |
Volume | 95 |
Issue number | 1 |
DOIs | |
State | Published - May 1 1980 |
Funding
This work was supported by the Division of Basic Energy Sciences,U S Department of Energy, ER-78-S-024946 and in part by a starter grant from the Cottrell Research Corporation. The use of the Central Facilities of Northwestern University’s Material ResearchC enter, supportedu nder the NSF-MRL programg rant DMR 76-80847f acilitated this work.
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry