1

WG1 Synthesis and Photocataysis will generate efficient strategies towards stabilization of the catalytic centers (both for proton reduction and water oxidation) in all required redox states within the ligand scaffold provided by the supramolecular photocatalyst (SPC). This presents a central challenge, since well-stabilized catalytic centers present an indispensable prerequisite for long-term operating catalytic systems.

The development of SPCs for photocatalytic water oxidation is a very challenging task for which ligand frameworks will be generated to stabilize the highly oxidized metal centers and which are inert towards being oxidized/reduced by the metal centre during the catalytic turn-over. Furthermore, the incorporation of light-harvesting functionalities into the framework of the SPCs will be researched. Such additional units will be designed to absorb light with high absorption cross-sections over a wide spectral range, and to subsequently transfer the energy to the photoactive primary electron donor. It will be investigated in collaboration with WG3, if artificial structures can be designed, which are capable of coherent energy transfer – a process recently discovered in natural light-harvesting systems and considered to be (partially) responsible for their high light-collecting efficiency. Moreover, the ligand structures to be developed will need to be designed to be stable under illumination in a wide pH-range and in the presence of the oxidation/reduction products of the sacrificial electron donors/acceptors. Strong collaboration with WG 3 and 4 is needed to i) determine structure-reactivity relationships and ii) optimize the ligand framework modifications. A very intriguing aspect for ligand design is the aspect of the second coordination sphere. Especially proton-donor/acceptor functionalities in close proximity to the reaction center can assist in proton coupled electron transfer events that occur in the first metal coordination sphere, and in doing so can raise the catalytic activity by several decades.

The current state-of-the-art of the field often involves rare (and toxic) metals, which will ultimately limit any subsequent up-scaling and a wide-spread application of SPCs. To cope with this problem, WG1 will work towards integrating both photoactive organic dyes and abundant metals, e.g., Mn, Fe and Ni into functional SPCs and SPC-based photoelectrodes. 

Of central importance are photocatalytic experiments. The synthesized SPCs will be tested in either the water oxidation or proton reduction catalysis under illumination with visible light. Isolation of decomposition products should help to identify the weak points of the ligand architecture that need to be optimized for long-term stability, and assist the research in WG4.

 

Contact

Workgroup Leader: Prof. Sven Rau

Ulm University
Albert-Einstein-Allee 11
89081 Ulm, GERMANY

Phone: This email address is being protected from spambots. You need JavaScript enabled to view it.

Phone: +49 - 731 - 50 22575

Fax: +49 - 731 - 50 23039 

 http://www.uni-ulm.de/nawi/nawi-anorg1/