Hydrodesulfurization (HDS) is an ubiquitous part of oil refining that ensures that fuels are cleaned of impurities and environment release of pollutants such as SOx and NOx gasses are minimized. In... Show moreHydrodesulfurization (HDS) is an ubiquitous part of oil refining that ensures that fuels are cleaned of impurities and environment release of pollutants such as SOx and NOx gasses are minimized. In this thesis, atomic level insights into the process of HDS are gained by exploring various methods of generating the catalytically active CoMoS phase as well as the effect of the reaction gasses like hydrogen and methylthiol on the atomic structure of the catalyst at industrially relevant conditions. For this purpose, a variety of techniques such as high-pressure scanning tunneling microscopy, X-ray photoelectron spectroscopy and electron diffraction are used. Furthermore, the studies presented in this thesis make several steps towards bridging the pressure and materials gap between the fundamental catalysis studies and industrial catalytic conditions. The results of this work pave way for more fundamental research with the help of theoretical methods such as DFT calculations which can help with designing more efficient catalysts to meet the future demands of clean fuels. Show less
Stability of quantum dot (QD) films is an issue of concern for applications in devices such as solar cells, LEDs, and transistors. This paper analyzes and optimizes the passivation of such QD films... Show moreStability of quantum dot (QD) films is an issue of concern for applications in devices such as solar cells, LEDs, and transistors. This paper analyzes and optimizes the passivation of such QD films using gas-phase deposition, resulting in enhanced stability. Crucially, we deposited alumina at economically attractive conditions, room temperature and atmospheric pressure, on (1,2-ethanediamine) capped PbSe QD films using an approach based on atomic layer deposition (ALD), with trimethylaluminum (TMA) and water as precursors. We performed coating experiments from 1 to 25 cycles on the QD films, finding that alumina formed from the first exposure of TMA. X-ray photoelectron spectroscopy points to the presence of oxygen-rich compounds on the bare QD films, most likely from entrapped solvent molecules during the assembly of the QD films. These oxygenated compounds and the amine groups of the organic ligands react with TMA in the first cycle, resulting in a fast growth of alumina. Using 10 cycles resulted in a QD film that was optically stable for at least 27 days. Depositing alumina at ambient conditions is preferred, since the production of the QD films is also carried out at room temperature and atmospheric pressure, allowing combination of both processes in a single go. Show less
