Modular design of a bioinspired tandem cell for direct solar-to-fuel conversion (Solarfueltandem)

The principle objective of this CRP is the modular design of a bio-inspired nanostructured organic-inorganic heterojunction tandem cell for solar to fuel conversion. The vision is to work from a combination of natural and artificial modules for catalysis and charge separation and explore a range of different combinations for functional tandem device concepts. This allows us to work in parallel on modular systems integration and optimization of components.
Self-assembled Zn chlorin nanocylinders forming excitations with internal charge transfer character will be aligned in an alumina solid membrane to form a supramolecular sensitizer for ultrafast charge separation and charge injection into a low-bandgap Si semiconductor. In this heterojunction system, two regions of the solar spectrum can be used in tandem to overcome the thermodynamic barrier for water oxidation and hydrogen production with visible light in a single device. Two complementary synthetic strategies will ensure access to a wide library of Zn chlorins.
Post-functionalization of Chl a and BChl c will ensure rapid preparation of compounds for self-assembly and photophysical studies, also with 13C labels. Total synthesis will give full control over the pattern of substituents for fine-tuning of all required physicochemical properties. We will use most sturdy natural PS2 and Pt modified PS1 systems from C. merolae with a very high photosynthesis rate as working photocatalysts for optimization of catalyst interfacing to semiconductors. In a parallel supramolecular approach we will prepare homogenous Ru/Ir/Co water oxidation and Fe/Ni/Co hydrogen formation catalysts for immobilization and interfacing to natural and artificial electron transfer units. Optical spectroscopy, NMR, EPR, electrochemistry, X-ray crystallography and modeling will be used to assess the kinetics of the multi-electron catalysis and dual band gap electron transfer mechanisms to guide the design.
The final aim of the CPR is to give proof of principle of a functional tandem device.