A comparative study of platinum nanodeposits on HOPG (0001), MnO(100) and MnOx/MnO(100) surfaces by STM and AFM after heat treatment in UHV, O2 , CO and H2

Abstract

This thesis aimed at preparing and characterizing two different model catalysts after their exposure at different temperatures to oxygen, carbon monoxide and hydrogen. The experiments were performed in an ultra-high vacuum (UHV) set-up using a range of techniques including scanning tunneling and atomic force microscopy. The first part of the thesis deals with platinum deposited onto highly oriented pyrolytic graphite (HOPG). It was found that a sub-monolayer of the deposited metal on this substrate forms randomly distributed two-/three-dimensional particles. Analysis of the morphology and height distribution of Pt particles on the HOPG(0001) surface after annealing in UHV and in the presence of low pressures of oxygen, carbon monoxide and hydrogen indicates that their growth proceeds via coalescence. The second part of the thesis is devoted to the preparation of model manganese oxide surfaces starting with the MnO(100) surface, which were used as a support for Pt deposits. The preparation of manganese oxide surfaces was based on annealing of MnO(100) single-crystals at different temperatures in UHV and in the presence of argon, oxygen and hydrogen. The first results of Pt deposition on the MnO(100) surface and on this surface altered by annealing in the presence of oxygen and hydrogen are described.