12 Jan. Molecule for artificial photosynthesis
At the University of Basel, researchers have presented a molecule that stores two positive and two negative charges simultaneously when exposed to light. This process is considered a key step towards artificial photosynthesis, which could enable CO2-neutral fuels in the long term. Professor Oliver Wenger and Mathis Brändlin report on the results in Nature Chemistry.
Plants convert carbon dioxide and water into sugar through photosynthesis, thereby storing solar energy in chemical form. For years, researchers have been pursuing the goal of replicating this process technically in order to produce solar fuels such as hydrogen, methanol, or synthetic gasoline. When such fuels are burned, they release only the amount of CO2 that was previously bound during their production. This means they are considered climate-neutral.
Quadruple charge generated in two flashes
The molecule from Basel consists of five segments: two building blocks release electrons when exposed to light and become positively charged. Two opposite units absorb electrons and become negatively charged. A central element absorbs the light and triggers the electron transfer. This allows the energy of photons to be specifically converted into chemical storage processes.
The scientists generated the four charges in two steps. A first flash of light led to a positive and a negative charge, which migrated to opposite ends of the molecule. A second light flash repeated the process, resulting in a total of two positive and two negative charges. This made it possible to stably store a double charge pair in a single molecule.
Mathis Brändlin explains: “This step-by-step excitation allows us to use much weaker light. We are already approaching the intensity of sunlight.” He pointed out that previous experiments required extremely strong laser light. “In addition, the charges remain stable in the molecule long enough to be used for further chemical reactions.”
A complete artificial photosynthesis process has not yet been achieved, but the new results should help improve scientists’ understanding of electron transfers in such molecules.
Original publication
[M. Brändlin, B. Pfund, O. S. Wenger: Photoinduced double charge
accumulation in a molecular compound, Nature Chemistry (2025), DOI: 10.1038/s41557-025-01912-x]
Source: www.unibas.ch
Image: Deyanira Geisnæs Schaad