Researchers have successfully split water into hydrogen (H2) and oxygen (O2) by altering the photosynthetic machinery in plants, a finding that could revolutionise renewable energy production.

A new study led by academics at St John’s College, University of Cambridge, used semi-artificial photosynthesis to explore new ways to produce and store solar energy.

They used natural sunlight to convert water into H2 and O2 using a mixture of biological components and human-made technologies. It also managed to absorb more solar light than natural photosynthesis, the process plants use to convert sunlight into energy. O2 is a by-product of natural photosynthesis and hydrogen is produced when the water is split.

“Natural photosynthesis is not efficient because it has evolved merely to survive so it makes the bare minimum amount of energy needed – around 1-2% of what it could potentially convert and store,” said Katarzyna Sokól, first author and PhD student at St John’s College.

A paper in Nature Energy explains how academics at the Reisner Laboratory in Cambridge achieved unassisted solar-driven water-splitting.

“This work overcomes many difficult challenges associated with the integration of biological and organic components into inorganic materials for the assembly of semi-artificial devices and opens up a toolbox for developing future systems for solar energy conversion,” said Dr Erwin Reisner, Head of the Reisner Laboratory, a Fellow of St John’s College, University of Cambridge, and one of the paper’s authors.

Sokól and the research team improved on the amount of energy produced and stored as well as managing to reactivate a process in the algae that has been dormant for millennia.

“Hydrogenase is an enzyme present in algae that is capable of reducing protons into hydrogen,” she said.

“During evolution this process has been deactivated because it wasn’t necessary for survival but we successfully managed to bypass the inactivity to achieve the reaction we wanted – splitting water into hydrogen and oxygen.”

This model is the first to successfully use hydrogenase and photosystem II to create semi-artificial photosynthesis driven purely by solar power.

Sokól hopes the findings will enable new innovative model systems for solar energy conversion to be developed.

“It’s exciting that we can selectively choose the processes we want, and achieve the reaction we want which is inaccessible in nature,” she said.

“This could be a great platform for developing solar technologies. The approach could be used to couple other reactions together to see what can be done, learn from these reactions and then build synthetic, more robust pieces of solar energy technology.”