Školitel: RNDr. Peter Matvija, Ph.D.
Stav práce: volná
Anotace:
Understanding the adsorption and activation of weakly interacting molecules, such as CO₂, N₂, and CH₄, on solid surfaces is a critical step in engineering effective systems for processing these chemicals. Catalysts based on abundant and relatively inexpensive metals (e.g., Ni, Cu, Fe) or their oxides are frequently employed in various chemical reactions involving these molecules, such as dry reforming of methane, CO₂ methanation, water-gas shift reaction, and ammonia production [1].
In past research, industrial catalysts were predominantly studied as relatively complex powder samples. These catalysts, with their high active surface areas, made it easier to quantify their activity and optimize their composition through trial and error. However, the complexity of these powder samples made it challenging to determine the exact reaction mechanisms responsible for catalytic activity. To address this, simplified model catalytic surfaces, often in the form of single-crystal samples or epitaxial layers, were later used to identify precise reaction pathways. Many traditional surface science techniques, however, require ultra-low pressure conditions for their operation. As a result, studies were often conducted either during direct exposure to very low pressures of reactants or characterized only before and after exposure to high pressures. It is now understood that surfaces can significantly reconstruct under high reactant pressures, highlighting the need to conduct experiments directly under high-pressure conditions to accurately observe the real reaction pathways that facilitate high rates of industrial reactions [2, 3].
In this thesis, we aim to prepare well-defined model single-crystal samples (e.g., Ni(111), Cu(111), Pt(111)). These surfaces will be characterized using in-situ/operando spectroscopic and atomically resolved microscopic methods (NAP-XPS/UPS, NAP-STM/AFM) [3, 4, 5] in the presence of weakly interacting molecules. Emphasis will be placed on conducting experiments across various flow regimes, including static pressure, dynamic flow of reactants, and the introduction of common contaminants. These different flow regimes will allow us to distinguish the effects of weakly interacting molecules from those of low-concentration contaminants, which may exhibit significantly higher reactivity. The results obtained from these advanced experimental techniques, combined with theoretical calculations, will provide a more comprehensive understanding of the mechanisms governing the behavior of these catalysts in reactive environments, paving the way for the development of more efficient catalytic systems.