[Zurück]

H. Li, C Weilach, G. Rupprechter:
"lnteraction of water with Zr02 ultrathin film-from UHV to elevated pressure";
Vortrag: 19th International Vacuum Conference (IVC-19), Paris; 09.09.2013 - 13.09.2013; in: "19th Inernational Vacuum Conference", IUVSTA, (2013).

lntroduction
Zr02 is known as an excellent support in the methane steam reforming. Particularly,
the interaction of water and Zr02 is of great importance, as the hydroxyl group might
influence the sintering of supported Ni, or participate in the reforming reaction [1 ]. In
order to conduct fundamental studies on Zr02 using a surface science approach, thin
film model catalysts have been prepared and their interaction with water have been
studied both under UHV and at elevated pressure.
Experimental
The ultrathin Zr02 film was prepared following a route proposed by Schmid and
coworkers [2]. The structure and the chemical composition of the film were
characterized by Low Energy Electron Diffraction (LEED) and high resolution X-ray
Photoelectron Spectroscopy (XPS), respectively. Thereafter, the film was exposed to
10 L water at 100 K for monolayer water studies, and to high pressure water in the
range from 10-6 mbar to 10-1 mbar at 300 K for in-situ studies. Temperature
Programmed Desorption (TPD) was used to investigate the dissociation of water
upon heating, and XPS was used to study the hydroxylation of the film. Besides,
defective films prepared by soft sputtering of the pristine film were also studied.
Results
LEED and XPS showed the formation of a well-structured Zr02 film. In case of the
monolayer water studies, TPD showed a 02 desorption peak between 200 K and 400
K. And on the defective film, XPS showed the development of a shoulder, ascompared to the single 0 1 s peak obtained from the pristine film, as shown in Fig.1.
For the high pressure studies, TPD gave a broad D2 desorption peak between 350 K
and 650 K. In Fig.2, XPS showed that the above mentioned shoulder developed into
a separated peak, which might be attributed to hydroxyl groups.
[1] Y. Matsummura, T. Nakamori, Applied Catalyis A: General 2004, 258, 107-114;
[2] M. Antlanger et.al, Physical Review B 2012, 86, 03451(1 )-03451(9).

ZrO2, Thin film