(P4F5 and P4F5A)
The study program covers all aspects of surface physics and thin film technology. It is based on knowledge of physical and chemical properties of solid state surfaces and interfaces and of physical processes related. Studies include problems of basic research in material science and nanophysics, study of surface structures and processes at atomic level, surface catalysis as well as borderline disiplines such as fuel cell technology. Experimental approach is in close relation with theoretical study of problems. The program prepares professionals with a broad foundation in physics, with rich experience in advanced surface experimental techniques and with deep knowledge of surface physics and chemistry.
Research fields are more or less defined by the current projects at our department and it similarly applies to the cooperating institutes of Czech Academy of Sciences.
Nanomaterials group deals with the preparation and characterization of nanomaterials. It aims especially for efficient catalysts for fuel cells and electrolyzers as well as for gas or bio sensors:
Thin film Group is focused on STM/AFM characterization of interactions of single atoms and organic molecules with various surfaces:
Surface Physics Group is focused on the investigation of physicochemical properties of technologically relevant surfaces and surface nanostructures:
It's always a good idea, if you find a topic for you, to contact supervisor first, i.e., prior application!
Supervisor: Ing. Nataliya Tsud, Dr.
The rapid progress of nanotechnology in the field of bioapplications and organic electronics brings in front the need to attach bio- or organic molecules to inorganic materials. The nanoworld implies the use of minimal quantities of molecules as well as substrates, thus the formed interface plays a crucial role in the physicochemical properties of a system. Chemical functionalization of metal oxide surfaces by covalent attachment of molecules is one of the most general strategies for the synthesis of new materials for nanotechnology.
In this work Pt-doped cerium oxide films are proposed as a complex system with excellent biocompatible, non-toxic and catalytic properties. Cerium oxide itself is an active support for catalytic metals, organic or biomolecules. Platinum plays a crucial role in many catalytic and electrocatalytic systems and also possesses a wide range of antioxidant properties. The Pt-doped CeO2 has many potential advantages, but there is very limited data on the effect of the combined use of platinum and cerium dioxide with bio- and organic molecules. Taurine, histidine and lysine are among the possible biomolecules, that efficiently model the organic molecule with sulfonate and carboxylate linker groups. In addition, the ciliatine molecule will be considered as a molecule with a phosphonate anchor group.
The polycrystalline CeO2 thin films will be prepared by magnetron sputtering technique. This approach will also allow us to directly dope or adsorb controlled amounts of Pt metal onto CeO2 to form metal species ranging from dispersed single atoms or clusters adsorbed on the oxide surface to atoms incorporated into the oxide crystal lattice. The film morphology will be analysed by scanning electron microscope, transmission electron microscopy or atomic forse microscopy. We will explore the functionalization of CeO2 with the above mentioned small model molecules that, unlike bulky polymers, allow the oxide surface to chemically interact with the surrounding environment. The molecules will be deposited in ultra-high vacuum and/or from solutions. Photoelectron-based surface science techniques, including ultra-high vacuum and near-ambient pressure X-ray photoelectron spectroscopies, will then be used to study how the molecules are bound to the oxide surface. The role of Pt in the molecular bonding to the surface will be elucidated. The main goal is the development of strategies for the surface functionalization of cerium oxide in a nanostructured form for bio and organic applications.
Supervisor: RNDr. Peter Kúš, Ph.D.
Modern society increasingly relies on renewable energy sources. The intermittent nature of wind and solar power generation requires efficient energy storage and release. The hydrogen economy offers an ideal solution by converting electricity into hydrogen via water electrolysis and later utilizing the stored hydrogen in industrial applications, transportation, or reconverting it into electricity via fuel cells when needed.
Water electrolyzers (WEs) rely on nanostructured catalysts to drive electrochemical water splitting into hydrogen and oxygen [1]. It is essential to make these catalysts as durable, cost-effective, and active as possible. This dissertation will build on the promising results of the Nanomaterials Group, particularly in the development of bimetallic and segmented nanostructures prepared using multi-target magnetron sputtering [2].
The focus will be on operando characterization, including in-cell X-ray photoelectron spectroscopy [3], in-cell X-ray diffraction [4], and electrochemical impedance spectroscopy, to monitor the potential-induced physicochemical and structural evolution of the prepared catalysts. These methods will provide unprecedented insight into complex processes that can only be directly observed during individual reactions. The efficiency of the studied catalysts will be investigated in parallel using conventional single cells under industrial operating conditions, with complementary analyses routinely performed using standard lab-based methods.
Supervisor: RNDr. Peter Matvija, Ph.D.
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.
Supervisor: RNDr. Peter Matvija, Ph.D.
Catalysts, substances that increase the rate and selectivity of chemical reactions without undergoing any permanent chemical change, are directly or indirectly involved in the production of about 90% of all chemicals and materials. Catalysts based on cerium oxide (ceria, CeO2) are highly effective due to their ability to switch between Ce3+ and Ce4+ states [1]. This property, also known as oxygen storage capacity (OSC) [2], arises from point defects in the material, which include missing ions (vacancies), excess ions (interstitials) or foreign kind ions (substitutional dopants).
Generation of increased density of point defects via inclusion of foreign atoms in the ceria structure has been a strategy for fine-tuning catalytic properties of ceria for a long time. For instance, incorporation of metal additives, M = Zr, Fe, Ni, Cu etc., into the ceria generally leads to an increase in the OSC. This increase can be explained by the fact that while oxygen storage in undoped CeO2 is restricted to the surface, there is usually participation of bulk oxygen in the storage process of Ce-based mixed oxides [3]. The increase in OSC may also be influenced by other factors such as the formation of local metal-ceria compounds or oxygen spillover [3].
In previous research, industrial ceria-based materials have primarily been studied as relatively complex powder catalysts. These catalysts possess a high active surface area, facilitating the quantification of their activity and the optimization of their composition through trial-and-error methods. However, the inherent complexity of these powder samples complicates the precise assessment of the reaction mechanisms underlying their catalytic activity.
In this thesis we aim to prepare well-defined model epitaxial layers of ceria grown on single-crystal samples (e.g. Cu(111), Pt(111)). These layers will be modified by additional deposition or co-deposition of other metals. These surfaces will then be characterized using in-situ/operando spectroscopic and atomically resolved microscopic methods (NAP-XPS/UPS, NAP-STM/AFM) [4, 5]. Results of these cutting-edge experimental techniques combined with theoretical calculations will help us gain more comprehensive understanding of the mechanisms that govern the behavior of these catalysts in reactive environments, paving the way for the development of more efficient catalysts.
Supervisor: Yevheniia Lobko, Ph.D.
Such alternative and eco-friendly energy sources as the anion exchange membrane (AEM) fuel cells and water electrolyzers are very perspective, and comparably cheap. However, the weak point in this technology is a membrane.
The aim of this work is to overcome one of the key limitations of anion exchange membrane, namely water management combined with the improved mechanical and electrochemical performance. The new advanced polymer membranes (stable over a wide temperature range) will be elaborated by the polymer chemical modification and by poly(ionic liquid) incorporation and immobilization inside the polymer matrix. The membrane properties will be evaluated in terms of ion conductivity, mechanical stability and transport properties. The influence of the following factors, i.e. the ionic liquid structure (cation and anion), the mode and conditions of membrane preparation, will be taken into account. Surface-sensitive techniques, specifically scanning electron microscopy (SEM) and atomic force microscopy (AFM), will be utilized to perform a surface morphology analysis of the membranes. This analysis aims to investigate the influence of the surface roughness, homogeneity, and distribution of the polymer heterogeneous blocks or/and ionic liquids on the mechanical and transport properties of the membranes. The X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and Raman spectroscopy will be performed to study the surface chemistry and reactions of the AEMs due to provide insights into the chemical and electrochemical behavior of the membrane under operating conditions. Moreover, in-operando XPS in water electrolyzer mode will be used for the investigation of the hydroxide anions’ diffusion in the thin layer of the catalysts, as well as through the membrane. Electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) can be used to study the membrane's ion conductivity, charge transfer resistance, hydrogen and oxygen cross-overs, and durability in-situ.
By combining these surface studies with bulk membrane characterization techniques (such as thermally gravimetric analysis (TGA), differential scanning calorimetry (DSC), mechanical testing, etc.), it is possible to gain a comprehensive understanding of the AEM's properties and behavior, which can aid in the development of more efficient and durable AEM-based electrochemical systems. Particular attention will be paid on the preparation of membrane electrode assembly using ultrasonic spray-coating and Meyer rod techniques. The overall cyclic performance of the elaborated electrochemical system will be examined in electrolyzer and fuel cell modes.
The main goal of the work is the establishment of the relationship between the structure, morphology, activity, and durability of the AEM membranes in operando in both fuel cells and electrolyzer.
