Intelligent design of nanostructured materials forms the basis for high efficiencies of many applications. In this regard, 3D hierarchical niobium oxide nanostructures are investigated, as they form self-organized using a facile one-step synthesis approach. Electron microscopic investigations in combination with different spectroscopic methods are used to analyze these superstructures heading towards a better understanding of the forces involved in self-organization at the nanoscale.
The potential applications of silica nanotubes (SNT) are various including gas storage, drug delivery and catalysis to name only a few. In this project, we focus on the study of silica-based nanotubes (SBNTs) which tend to assemble to 3D mesostructures. The structural and chemical compositions of these networks as well as their internal morphology are investigated by transmission electron microscopy (TEM) techniques with a main focus on electron energy loss spectroscopy (EELS).
TiO2 nanostructures are promising electrode materials for dye or hybrid solar cells. Among a great variety of nanostructures, single-crystalline TiO2 nanowires exhibit particularly interesting characteristics. In this project TiO2 nanowires are sythesized via a hydrothermal approach and analyzed using electron microscopy. The main focus is on the morphology changes during annealing, which lead to better performance.
The search for alternative energy sources is growing steadily. Among many suitable materials copper indium disulfide, CuInS2, is a promising material. In our studies it is synthesized via a solvothermal synthesis. This method allows to grow solid materials at low temperatures. To investigate the properties of the synthesized samples mainly electron microscopic techniques, like transmission or scanning electron microscopy (TEM and SEM, respectively), are used.
Metals are ductile and ceramics are stiff. Ideally, these advantageous properties of each material class can be combined in one material. Examples are nanolaminated systems such as Mo2BC. In this project, we focus on the investigation of the micro- and nanostructure of Mo2BC before and after mechanical test using electron microscopy methods.
The progressing climate change on the one hand and our increasing demand of energy supply combined with a decreasing stock of natural resources on the other hand constrain us to focus on alternative, renewable energy suppliers. One of the many viable solutions therefore are fuel cells (FCs) which are devices that enable us to convert the chemical energy of a fuel into electrical energy via catalyzed reactions on electrodes. This project focusses on high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs).
Thin films are used in a variety of technologies, e.g. as coatings or for microelectronic applications. Miniaturization and the eventually high surface to volume ratio might enhance thin film degradation. Understanding and controlling of the underlying processes will help to establish reliable and controlled devices or new scopes of application. In this project, we focus on well-defined aluminum thin films as model system and their solid state dewetting behavior.
Thermoelectrics have attracted increasing attention as a sustainable and flexible source of electricity able to meet a wide range of power requirements. Their application is wide as they could be used in automotive, aerospace, power plants and medical fields, and wherever temperature gradients exist. In this project we focus mostly on the ternary Ag–Sb–Te system as it is a promising thermoelectric (TE) material that can be used to convert waste heat into electrical energy. The Ag-Sb-Te compounds possess high ZT-values and are subsystems of the very promising quaternary compounds Pb-Ag-Sb-Te (LAST) and (AgSbTe2)1-x(GeTe)x (TAGS).
While solar cells are becoming more and more widespread, storing the produced energy is difficult. Of the many possible solutions, the splitting of water into H2 and O2 by a photoelectrochemical cell offers an elegant approach. The hydrogen can then easily be stored, transported and burned in a fuel cell. As most features in photoelectrodes are on the nano- or microscale, electron microscopy is very powerful. We study material systems such as Fe2O3 or TiO2 and attempt to identify performance bottlenecks.