Abstract
Nanoparticles present different properties from those of bulk matter, as a result of both their large surface-area-to-volume ratio, and their electronic structure composed of discrete levels, instead of electronic bands. Their properties depend strongly on their size, charge state, and composition. Exploring the relationship between the structures and their properties is the first and fundamental step towards a rational design of metallic nanoparticles for a diverse range of applications. In order to achieve this, a deep understanding of the effects that size and composition play on such properties is needed.The work presented in this thesis centres on monometallic and single-doped particles of sizes between 3 and 1000 atoms. In particular, on how their geometrical and electronic structure affects their chemical and thermal stability. For the smaller sizes, the focus is on using density functional theory methods to study their electronic and geometrical stability. For the bigger sizes, the focus is on studying their structural evolution with increasing temperatures, using molecular dynamics.
A general introduction and state of the art is given in Chapter 1. An overview of the numerical methods and experimental techniques used throughout this thesis is given in Chapter 2. The first study on Chapter 3 centres on choosing the best density functional method to study the interaction of small metal clusters with argon. This benchmark study will set the standards for the next chapters. In Chapter 4, we study how doping with an atom of silver affects the geometry and the electronic structure of gold clusters, which in turn affects their stability. Chapter 5 studies how palladium doping influences the structure of gold clusters, concentrating nowon assigning their geometries, based on experimental data. Finally, in Chapter 6, we shift the focus towards bigger nanoparticles, with sizes from 100 to 1000 atoms. These are studied using molecular dynamics simulations to analyse their structural evolution at increasing temperatures. Final conclusions are given in Chapter 7 and an outlook is provided in Chapter 8.
| Date of Award | 1 Nov 2022 |
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| Original language | English |
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| Supervisor | Evgeny Kozik (Supervisor), Ewald Janssens (Supervisor), Peter Lievens (Supervisor), Piero Ferrari (Supervisor) & Kevin Rossi (Supervisor) |