A Swiss research team has successfully developed a molecule that can store two electrons using ordinary light, marking an important step towards artificial photosynthesis. The breakthrough, published in Nature Chemistry on August 25, demonstrates a donor-photosensitizer-acceptor pentad system that can trap a double charge state with 37% efficiency and hold it for up to 120 microseconds.
Currently, lab systems tend to move electrons one at a time, but the Basel team wanted to find a cleaner way to bridge this gap. Their molecule has five linked parts: two electron donors, a ruthenium bipyridine complex that absorbs light, and two electron acceptors. When a single photon triggers the charge split, an electron is sent across the structure, creating a long-lived state.
A second photon re-excites the ruthenium center, sending fresh charges to the second donor and acceptor. This results in four redox equivalents neatly parked on the molecule’s branches. The researchers used laser pump-probe experiments to track the charged states in real-time, observing a double charge state with a lifetime of at least 100 nanoseconds.
This design works under weaker light and uses sequential excitation, which is closer to what real solar energy provides. It opens the way for molecules that could one day drive water splitting or carbon dioxide reduction directly. The findings demonstrate an unprecedented scenario in which the charge accumulating step proceeds with the same high quantum yield as the initial charge separating step.
The breakthrough has significant implications for artificial photosynthesis, and further research is needed to unlock its full potential.
Source: https://scienceblog.com/breakthrough-in-mimicking-natures-multi-electron-photosynthesis