In the quest for carbon reduction, researchers at Switzerland’s University of Basel have created a molecule essential for artificial photosynthesis, the process of converting sunlight into stored energy.
The discovery, revealed in a new paper in Nature Chemistry, solves a major problem for artificial photosynthesis: the need to store multiple charges. The newly designed molecule can simultaneously hold two positive and two negative charges, marking a significant step toward sustainable energy technologies.
Photosynthesis
Photosynthesis, the foundation of most life on Earth, allows plants to transform carbon dioxide into carbohydrates using sunlight. This energy is then passed up the food chain as animals consume plants and other animals, releasing carbon dioxide back into the atmosphere in the process.
Modern industrial energy sources, however, generate vast amounts of carbon dioxide without a comparable mechanism to recycle it, leading to an excess of greenhouse gases. The University of Basel team aims to mimic nature by harnessing sunlight to produce high-energy, carbon-neutral solar fuels, including hydrogen, methanol, and synthetic gasoline. The aim is to replicate photosynthesis, ensuring that fuels release only as much carbon as is required to produce them.
An Artificial Molecule
Professor Oliver Wenger, along with his doctoral student, Mathis Brändlin, reported success in this early phase of their artificial photosynthesis research. Under light irradiation, their molecule successfully stored four charges, a crucial precursor to energy conversion. The next step will be to use that stored energy to drive reactions such as splitting water into hydrogen and oxygen.
Wenger and Brändlin designed their molecule to consist of five linked parts, each with a specific function. At its core lies a section responsible for absorbing sunlight and initiating the electron transfer process. On one side, two units capture electrons and gain negative charges, while on the other, two segments release electrons, creating positive charges.
Energy in Two Steps
When exposed to a pair of light flashes, the molecule produces the four charges in a two-step process. The initial burst of light triggers the energy-generating reactions, birthing a positive and negative charge, which then journey to the molecule’s opposite ends. With another flash, the reaction repeats, filling the molecule with two of each charge.
“This stepwise excitation makes it possible to use significantly dimmer light. As a result, we are already moving close to the intensity of sunlight,” explains Brändlin, who notes that earlier research required extremely strong laser light, which was a far cry from the vision of artificial photosynthesis.
“The charges in the molecule remain stable long enough to be used for further chemical reactions,” Brändlin added.
The team’s work offers important insights into electron transfer mechanisms, though a fully functioning artificial photosynthesis system remains a goal for future research.
Still, as Wenger notes, “we have identified and implemented an important piece of the puzzle,” adding that he and Brändlin “hope that this [research] will help us contribute to new prospects for a sustainable energy future.”
The paper, “Photoinduced Double Charge Accumulation in a Molecular Compound,” appeared in Nature Chemistry on August 25, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.