Scientists pioneer a
new way to turn sunlight into fuel
The quest to find new ways to harness solar power has taken a step
forward after researchers successfully split water into hydrogen and oxygen by
altering the photosynthetic machinery in plants.
Photosynthesis is the process plants use to
convert sunlight into energy. Oxygen is produced as a by-product of
photosynthesis when the water absorbed by plants is ‘split’. It is one of the
most important reactions on the planet because it is the source of nearly all
of the world’s oxygen. Hydrogen which is produced when the water is split could
potentially be a green and unlimited source of renewable energy.
A new study, led by academics at the 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 hydrogen and oxygen
using a mixture of biological components and manmade technologies.
The research could now be used to
revolutionise the systems used for renewable energy production. A new paper,
published in Nature Energy, outlines how academics at the Reisner
Laboratory in Cambridge's Department of Chemistry developed their platform to
achieve unassisted solar-driven water-splitting.
Their method also managed to absorb more
solar light than natural photosynthesis.
Katarzyna Sokół, first author and PhD student
at St John’s College, said: “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 per cent of what it could potentially convert and store.”
Artificial photosynthesis has been around for
decades but it has not yet been successfully used to create renewable energy
because it relies on the use of catalysts, which are often expensive and toxic.
This means it can’t yet be used to scale up findings to an industrial level.
The Cambridge research is part of the
emerging field of semi-artificial photosynthesis which aims to overcome the
limitations of fully artificial photosynthesis by using enzymes to create the
desired reaction.
Sokół and the team of researchers not only
improved on the amount of energy produced and stored, they managed to
reactivate a process in the algae that has been dormant for millennia.
She explained: “Hydrogenase is an enzyme
present in algae that is capable of reducing protons into hydrogen. 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.”
Sokół hopes the findings will enable new
innovative model systems for solar energy conversion to be developed.
She added: “It’s exciting that we can
selectively choose the processes we want, and achieve the reaction we want
which is inaccessible in nature. 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.”
This model is the first to successfully use
hydrogenase and photosystem II to create semi-artificial photosynthesis driven
purely by solar power.
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 described the research as a ‘milestone’.
He explained: “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.”
Katarzyna P. Sokół
https://www.cam.ac.uk/research/news
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