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Photo- and Redox-Active Systems
Photonic and redox-active systems for photosynthesis form the basis of (almost) all life on Earth, and photoactive systems for photocatalysis are expected to play a key role in transforming the economy towards a carbon-free and sustainable energy generation—ensuring that life as we know it can continue to exist on our planet. Photosynthesis is the fundamental biological process by which plants, algae, and some bacteria use sunlight to synthesize energy-rich compounds such as glucose and produce oxygen as a by-product. Photocatalysis for converting solar energy into electrical energy—for example, in dye-sensitized solar cells—and for storing energy in the form of hydrogen are two promising approaches to generating energy in an environmentally friendly way.
To better understand and specifically optimize these processes, spectroscopic methods are essential. These are being researched in the working group on photo- and redox-active systems. Techniques such as time-resolved spectroscopy provide insight into ultrafast electron transfer processes, while (resonance) Raman spectroscopy can detect accompanying structural changes. In combination with electrochemical methods, reactive intermediates in complex, multi-step electron transfer cascades can be thoroughly analyzed. In addition to spectro-electrochemical techniques, another focus of the group is to capture time-resolved spectral information with high spatial resolution to elucidate electron transfer at photo- and redox-active structures. The group also focuses on developing novel, highly sensitive, and multimodal combinations of various spectroscopic and preparative techniques and applying them to the investigation of photo- and redox-active systems.
Optical spectroscopic setup for characterization of light-induced processes.
Selected Research Topics
In this research group, these methods are used to investigate molecular systems—particularly in complex environments—as well as thin (including molecular) layers and interfaces, all the way to complex three-dimensional structures and components functionalized with photoactive molecules. The aim is to analyze and better understand the structure, charge transfer dynamics, and function of these systems. The research questions stem from the fields of materials science and catalysis and include:
Resonance) Raman spectroscopy for structural elucidation of photoactive systems
Development and implementation of novel spectroscopic and combined spectro-electrochemical techniques for studying charge transfer processes
Electrochemical generation of intermediates in photocatalytic processes and their investigation using time-resolved optical spectroscopy
- Development of preparation methods for producing reactive species involved in multi-step charge transfer processes
Time-resolved emission imaging and transient absorption microscopy for spatially resolved analysis of charge transfer processes
Analysis of functional materials, such as self-healing systems
In operando spectroscopic characterization of charge transfer processes
Investigation of charge transfer in noble-metal-free catalyst systems such as polyoxometalates
Time-resolved optical, spectroscopic, and electrochemical methods are being developed and combined to analyze multi-step electron transfer processes in molecules, solids, and at interfaces. The technological and methodological focus of the research lies in enabling the detailed monitoring of such charge transfer processes at very low concentrations with the highest temporal resolution. To achieve this, the group is working on methods to stabilize reactive species under inert conditions or at low temperatures for extended measurement periods, as well as on increasing the sensitivity of spectroscopic techniques.
Areas of application
- Basic Research on Photocatalysts
- In operando spectroscopy on molecular catalyst systems
- Elucidation of photocatalytic processes for green hydrogen production
- Mechanistic understanding of light-driven reactions
- Spatially and temporally resolved characterization of photoinduced charge transfer processes in functional materials and at interfaces
- Investigation of photoelectrodes