Artificial photosynthesis: Chemists develop dye stacks that mimic energy conversion in plants

Artificial photosynthesis allowed humans to use solar energy to combine carbon dioxide and produce hydrogen. Chemists from Würzburg and Seoul took this one step further. They synthesized a stack of dyes that is very close to the plant’s photosynthetic devices. It absorbs light energy and uses it to isolate charge carriers, transferring quickly and efficiently within the stack.

Photosynthesis is an amazing process. Plants use it to produce sugar molecules and oxygen from simple starting materials carbon carbon and water. They draw the energy needed for this complex process from sunlight.

If humans can mimic photosynthesis, there are many benefits. Free energy from the sun can be used to remove carbon dioxide from the atmosphere and use it to construct carbohydrates and other useful substances. Hydrogen can also be produced because photosynthesis divides water into the components oxygen and hydrogen.

Photosynthesis: A complex process with many participants

Therefore, it is no wonder that many researchers are working on artificial photosynthesis. This is not easy as photosynthesis is a very complicated process. It occurs in plant cells in many individual steps and involves numerous dyes, proteins and other molecules. However, science is constantly making new advances.

One of the leading researchers in the field of artificial photosynthesis is Professor Frank Würsner, a chemist at Julius Massimilian Universitat (JMU) Würzburg in Bavaria, Germany. His team has managed to mimic one of the first steps in natural photosynthesis with a sophisticated arrangement of artificial dyes, and more accurately analyze it.

The results were obtained in collaboration with Professor Dongho Kim’s group of Yongpay University in Seoul (Korea). They are featured in Nature Chemistry.

Researchers have successfully synthesized a stack of dyes that is very similar to the photosynthetic device of plant cells. At one end it absorbs light energy, separates charge carriers, and moves stepwise to the other end via electron transport. The structure consists of four stacked dye molecules of the perylenebisimide class.

“The charge transport of this structure can be specifically triggered by light, and we analyzed it in detail. It is efficient and fast. This is an important step towards the development of artificial photosynthesis,” said Leander Ernst, a student who synthesized stacked structures.

Next, the JMU research team wants to expand the stacked dye molecule nanosystems from four components to more components. Ultimately, the aim is to create a kind of supramolecular wire that absorbs light energy and transports it quickly and efficiently over longer distances. This is an additional step into new photofusion materials that can be used in artificial photosynthesis.