Researchers from St. John’s College, University of Cambridge have developed a semi-artificial photosynthesis-based method to store and use solar energy. When developing the new method, the researchers successfully split water into hydrogen and oxygen by altering the way that photosynthesis operates in plants. The new method proved to absorb more light than completely natural photosynthesis.
Experimental two-electrode setup showing the photoelectrochemical cell illuminated with simulated solar light. Source: Katarzyna Sokó
Hydrogen is the key to the new solar energy method. The element is produced when water splits during photosynthesis, and researchers generally agree that it could be a new, unlimited source of green energy.
The team used semi-artificial photosynthesis to find new ways to produce and store solar energy. In semi-artificial photosynthesis, natural sunlight converts water into hydrogen and oxygen using biological components naturally found in plants combined with new, human-made technology. The team believes that semi-artificial photosynthesis could be used to create unassisted solar-driven water splitting and energy storage.
Katarzyna Sokó, first author and Ph.D. 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 percent of what it could potentially convert and store."
But semi-artificial photosynthesis uses catalysts. Catalysts are expensive and toxic, which is why semi-artificial photosynthesis isn’t widely used and hasn’t been able to be scaled up to the industrial level. The team overcame this problem by using enzymes and bacteria in place of the catalysts.
"Hydrogenase is an enzyme present in algae that is capable of reducing protons into hydrogen," Sokó explained. "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."
Sokó 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."
The new system is the first to successfully use hydrogenase and photosystem II to create semi-artificial photosynthesis that uses only solar energy.
"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 and a Fellow of St John's College.
The paper on this technology was published in Nature Energy.
