The work in this thesis demonstrates how to obtain an atomic-scale picture of a diverse set of complex surface structures observed using STM, under disparate conditions. Chapters 4−6 each represent... Show moreThe work in this thesis demonstrates how to obtain an atomic-scale picture of a diverse set of complex surface structures observed using STM, under disparate conditions. Chapters 4−6 each represent a different approach to answer the same question: How can we find out what a surface looks like at the atomic scale? By employing appropriate theoretical tools that complement the experimental conditions and measurement techniques, it is possible to compare the results from theory and experiment in an intuitive manner to obtain additional insights. Additionally, Chapter 4 shows that theoretical studies, which do not take experimental conditions into account appropriately, can lead to wrong conclusions. Show less
Katsounaros, I.; Costa Figueiredo, M.; Chen, X.; Calle Vallejo, F.; Koper, M.T.M. 2017
This thesis describes the construction of a second generation high-pressure, high-temperature scanning tunneling microscope, the ReactorSTM, with which the surfaces of catalysts can be studied... Show moreThis thesis describes the construction of a second generation high-pressure, high-temperature scanning tunneling microscope, the ReactorSTM, with which the surfaces of catalysts can be studied under relevant reaction conditions. Furthermore, the thesis describes three separate catalytic systems at ~ 1 bar, and elevated temperatures. Firstly, NO reduction on Pt(100), in which a mathematical model for the reaction mechanism, following Langmuir-Hinshelwood kinetics, is proposed. Secondly, CO oxidation, in which the Pt(110) surface is atomically resolved at high p, T. Thirdly, the thesis describes a successful pilot experiment about the hydrodesulphurization of thiophene, which is catalytically activated by molybdenum disulphide nano-crystallites on an Au(111) support. Show less
The main theme of this thesis is the catalytic oxidation of CO, which we have investigated on several model catalyst surfaces at atmospheric pressures and elevated temperatures with the combination... Show moreThe main theme of this thesis is the catalytic oxidation of CO, which we have investigated on several model catalyst surfaces at atmospheric pressures and elevated temperatures with the combination of Scanning Tunneling Microscopy and Mass Spectrometry.The study of CO oxidation on low-index and vicinal palladium surfaces has shown that when exposed to ambient pressures of oxygen at elevated temperature, these surfaces oxidize irrespective of their orientation. In this pressure regime the oxides were shown to have a higher reactivity than the metallic surfaces.In a certain window of partial pressure combinations of O2 and CO reaction rate oscillations were observed on Pd(100) and on its vicinal surface Pd(1.1.17). ). CO adsorption on Pt(111) was found to lead to the formation of a regular overlayer structure, identified as (√19 x √19) R23.4°-13CO. The stability of this structure under different reaction conditions was discussed. These results were further used to illustrate the importance of temperature in a catalytic system.Spectacularly high conversion rates could be achieved during CO oxidation at atmospheric pressure on metallic Pt(100) surface. Show less
