From the challenges of the energy transition to the ecological and economical production of many basic materials, heterogeneous catalysts are key materials in a variety of processes. Our goal is to develop hybrid material combinations of readily available elements for use as thermal and photochemical catalysts. We combine oxidic semiconductors (such as titanium dioxide) with inorganic or organic nanostructures.

Using defined model systems, we generate a microscopic understanding of relevant structure-property relationships, intermediates of relevant reaction pathways and potential deactivation mechanisms down to the atomic level by combining microscopic and spectroscopic methods. These results are the basis for further optimization of the hybrid materials and the transfer to technically scalable catalysts.

Our approach includes different levels of complexity: On one hand, we derive a deep atomic level understanding on well-defined model systems. On the other hand, the model system findings are transferred to industrially useable materials such as nano- and mesostructured powders, which are tested under more realistic conditions. However, since a deep characterization is not appropriately reachable under technical conditions, combining both sides yields the full view.

As the surfaces or interphases are most relevant for catalysis, surface science methods under ultra-high vacuum (< 10^-9 mbar) are combined with (near-)ambient pressure conditions, so called operando methods. We use the synergy of four types of methods to gain a comprehensive understanding and solve the puzzle:

• Spectroscopy: Photoelectron Spectroscopy (XPS), Vibrational spectroscopy (FTIR)
• Microscopy: Scanning Tunneling Microscopy (STM), Electron Microscopy
• Diffraction: Electron Diffraction (LEED), X-Ray Diffraction (XRD)
• Reactivity: Temperature-programmed Desorption Spectroscopy (TPD), Micro Reactors

These techniques efficiently balance out the advantages and drawbacks of each techniques, which are mainly defined by their spatial resolution, strength to identify elemental or molecular compounds, structural order and of course the detection reactions products and underlying kinetics. Thus, our studies are deeply coupled to the use of such state-of-the-art techniques, which we also apply on photocatalytic reactions. In all fields, theoretical modelling and simulations supplied by collaboration partners in theory groups are an indisputable contribution to support the experimental results.