Growth and reactivity of Zn and ZnO on Pd(111)

Abstract

In this work, the adsorption and reactivity of Zn and ZnO on Pd(111) have been investigated using scanning tunnelling microscopy, temperature programmed desorption, density functional theory and reflection absorption infrared spectroscopy. Using this approach, it was shown that an ordered PdZn surface alloy already forms at room temperature. The electronic structure of this surface alloy resembles that of copper. Depending on the preparation method and temperature, different surface alloys and Zn layers can be formed. The ZnO growth on Pd(111) forms different ZnO structures. Both a (4×4) and a (6×6) structure are formed depending on the oxygen pressure during ZnO growth. The (4×4) structure is most likely a hydrogen terminated Zn₆O₅ structure. In an attempt to verify the hydrogen termination, this structure and the (6×6) structure, which corresponds to a graphite-like Zn₆O₆ structure, were investigated using reflection absorption infrared spectroscopy. The results show a vibrational feature that could correspond to the O–H stretch vibration of the hydrogen terminated structure.

Keywords:

• Pd(111)
• Zn
• ZnO
• Adsorption
• Desorption
• STM

This work was funded by the Austrian Science Fund (FWF). H. P. Koch is indebted to the Austrian Science Society (Österreichische Forschungsgesellschaft ÖFG) for the MOEL project ‘Dichtefunktionaltheorie (DFT) Berechnungen der Methanol Zersetzung auf PdZn Oberflächen’. I. Bako is indebted for support from the Hungarian OTKA 168140.