In-situ AFM study of the crystallization and pH-dependent stability of ZnO(0001)-Zn surfaces
- PDF / 385,103 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 12 Downloads / 170 Views
1035-L13-02
In-situ AFM study of the crystallization and pH-dependent stability of ZnO(0001)-Zn surfaces Markus Valtiner1 and Guido Grundmeier1,2 1 Christian Doppler Laboratory for Polymer/Metal Interfaces, Max Planck Institut für Eisenforschung GmbH, Max-Planck-Strasse 1, Düsseldorf, Germany 2 Dept. for Technical and Macromolecular Chemistry, University of Paderborn, Warburgerstrasse 100, Paderborn, Germany ABSTRACT Polar ZnO(0001)-Zn surfaces can be prepared as very well defined and single crystalline surfaces by hydroxide stabilization simply by introducing hydroxides via a wet chemical cleaning step. Within this proceeding we present an in-situ AFM imaging of the crystallization process. The pH dependent stability of the resulting hydroxide-stabilized surfaces was further investigated by means of an ex-situ LEED approach. These investigations show, that it is possible to obtain high quality single crystalline ZnO(0001)-Zn surfaces in a simple way. Moreover, these surfaces turned out to be very stable within a wide range of pH values between 11 and 3 of NaClO4 based 1mM electrolyte solutions. INTRODUCTION The surface chemistry of oxide/liquid interfaces is a key issue in adhesion science and related areas such as corrosion science or electrocatalysis. ZnO is of particular interest in all these areas. The herein investigated single crystal ZnO(0001)-Zn surfaces have been extensively studied under UHV conditions within the last decades1-3. In contrast the literature on welldefined and crystalline ZnO(0001)-Zn surfaces under ambient conditions and in electrolyte solutions is not very comprehensive 4-7. In order to allow a defined study of oxide behavior we have been working on preparing well defined single crystalline ZnO(0001)-Zn surfaces for investigations under ambient conditions and within electrolytes. We were able to show that the polar ZnO(0001)-Zn surface can be prepared quite simple and efficient as a very well defined, single crystalline surface8. Within this proceeding we present our first in-situ studies of the crystallization process of the surface in highly alkaline etching/cleaning solutions. This very easy way of crystallizing the surface could be a promising pre-treatment approach in order to obtain a perfectly defined ZnO(0001)-Zn-OH surface for various applications. Furthermore, we could show that these crystalline surfaces are very stable in electrolytes by ex-situ LEED and ex-situ AFM studies. EXPERIMENT All chemicals were of p.a. grade (analytical reagent grade) and were used as supplied without any further purification. The water used for the experiments was de-ionized (18.2 MΩcm-1 resistivity) with a Purelab Plus UV (USF) filtration system. The hydro-thermally grown ZnO single crystals with ZnO(0001)-Zn polished faces ( 12 dissolution of ZnO is expected4, 5. ZnO constantly dissolves into the alkaline solution as [Zn(OH)4]2- complex. An interesting behavior is, that the polar ZnO(0001)-Zn surface
itself is intact against dissolution. Quite in contrast, the hydroxides in the solution stabili
Data Loading...
