How does sunlight split water during photosynthesis?

German researchers on the way to artificial photosynthesis

Mülheim an der Ruhr - The efficiency of natural photosynthesis is still unmatched when it comes to the use of solar energy. Researchers approach this energy conversion step by step. In the journal "Angewandte Chemie", German researchers are now proposing a new class of catalysts for using sunlight to split water directly into oxygen and hydrogen. In addition, the titanium disilicide used can even store the hydrogen generated in this way.

"Our catalyst splits water with a higher degree of efficiency than most other semiconductor systems that also work with visible light," says Martin Demuth from the Max Planck Institute for Bioinorganic Chemistry in Mülheim an der Ruhr. This is because the semiconductor material titanium disilicide captures a broad spectrum of sunlight and can use it directly to split water molecules. At the beginning of the catalysis reaction, a slight oxide formation on the titanium disilicide ensures the formation of the necessary catalytically active centers.

Demuth emphasizes another advantage of these catalysts. Because titanium disilicide can also store the hydrogen obtained. Other, porous storage materials are more effective, but titanium disilicide releases the hydrogen at significantly lower temperatures. The researchers are convinced of the marketability of this relatively inexpensive catalyst for hydrogen production using sunlight. That is why they have the processes patented and, together with American and Norwegian partners, founded a company for further development and marketing in Lörrach.