For a long time, engineers have been trying to copy biological photosynthesis. Their aim is to use the energy of the sun to separate energy-rich hydrogen from water. This would enable us to produce fuel for engines or fuel cells.

Artur Braun’s working group at Empa has taken a step closer to artificial photosynthesis. Braun is a biophysicist working on photo-electrochemical cells in which the semiconductor iron oxide is combined with proteins derived from cyanobacteria. Now his team has used X-rays to help them succeed in measuring the physical processes occurring between the biomolecules and the semiconductor.

“We can see the cell’s physical reactions on the surface in detail”, he says.Such experimental proof shows that two different strategies of artificial photosynthesis can be united: on the one hand we have the biochemists who put their hope in using biological molecules, and on the other hand we have the engineers who are recreating the biological system with inorganic materials.

Braun’s photo-electrochemical cell is thus comparable to the cell made by the solar pioneer Michael Grätzel of EPFL. “Our hybrid of animate and inanimate matter generates more hydrogen than pure iron oxide”, says Braun. Measuring these processes on the boundary between biomolecules and iron oxide is necessary in order to further the exploitation of biological energy systems that can regenerate themselves.

In Lausanne, Grätzel supports Braun’s strategy: “Their work with iron oxide and bacterial proteins has a promising future”, he says.