By mimicking nature, researchers have succeeded in producing hydrogen from water using sunlight, a virtually inexhaustible energy source — with a view to using it as a clean fuel.
It is what made life on the planet possible as we know it. Photosynthesis allowed plant organisms to colonise dry land and produce almost all the oxygen on Earth, thereby also favouring the emergence of humankind. A process that enables plants to synthesise sugars from carbon dioxide (CO2) and water, using sunlight as a clean and virtually infinite "fuel". A process on which scientists have long been working, in order to produce a green and virtually unlimited energy source. That is precisely what happened in the laboratories of St John's College, University of Cambridge, where researchers managed to recreate the same reaction that takes place in plants, splitting water molecules into oxygen and hydrogen with remarkable efficiency.
Replicating photosynthesis in the laboratory would make it possible to produce hydrogen in a clean, emission-free manner and virtually indefinitely (the remaining lifespan of the Sun is estimated at around another 4–5 billion years). Just as plants use hydrogen as a building block for the construction of sugars (energy), we could use it to power electric motors, batteries and much else besides. The research, published in Nature Energy, explains how the researchers succeeded in developing a process for achieving the separation of water through solar energy.
"Natural photosynthesis is not efficient because it evolved merely to survive, so it minimises the amount of energy needed — around 1–2 per cent of what it could potentially convert and store," said Katarzyna Sokół, lead author of the study and PhD student at St John's College, in a statement. Artificial photosynthesis has already been reproduced for decades, but has never been used for renewable energy production, because until now it relied on the use of catalysts that are both costly and toxic.
From the laboratories of St John's College, however, the research team succeeded in reactivating hydrogenase, an enzyme capable of reducing protons to hydrogen, present in algae but inactive for millennia because it was of no use to the species' survival. "During evolution this process was switched off because it was not necessary for [their] survival, but we managed to bypass the inactivity to obtain the reaction we wanted: splitting water into hydrogen and oxygen," the researcher explained.
Of course, this is only a very first step, even if the head of the University of Cambridge laboratory, Erwin Reisner, has described it as a "milestone". The goal is to eventually produce systems capable of converting solar energy efficiently, cleanly and without emissions, virtually indefinitely.