Artificial Photosynthesis

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Photosynthesis is one of the major processes in plants. Plants form energy in the form of sugar and oxygen as the product of sunlight, carbon dioxide, and water. Photosynthesis takes place in the chloroplast. Chloroplast contains a pigment called chlorophyll (which gives the green color of leaves). Overall, photosynthesis is a vast process that consists of many sub-processes.

Two prominent stages in photosynthesis are light-dependent reaction and light-independent reaction (Calvin cycle). The light-dependent reaction takes place in the thylakoid membrane of the chloroplast and the Calvin cycle takes place in the stroma.

Over the last two decades, chemists have made great progress in developing photocatalytic catalysts that can absorb energy from light. These catalysts give the reaction the extra energy it needed to be carried out. Researchers have used molecules to perform both light absorption and catalysis. But this isn’t possible as naturally separate processes.

Recently, at the Massachusetts Institute of Technology (MIT), researchers have developed new photocatalysts that can absorb light and trigger a variety of chemical reactions, the photo-driven process that plants use to produce sugar. These new photocatalysts, known as biohybrid photocatalysts, contain light-collecting proteins that absorb light and transfer energy to metal-containing catalysts. And later this catalyst uses that energy to carry out the reaction. “By replacing harmful conditions and reagents with light, photocatalysis can make pharmaceutical, agrochemical, and fuel synthesis more efficient and environmentally compatible, " says Gabriela Schlau-Cohen, an associate professor of chemistry at MIT.

Scientists wanted to make a biohybrid catalyst, which would do both the processes together, so it was decided to take inspiration from photosynthesis and combine two separate elements: one is collecting light and the other is for catalyzing chemical reactions. For the light-harvesting component, they used a protein called R-phycoerythrin (RPE), found in red algae. They attached this protein to a ruthenium-containing catalyst, which had been previously used for photocatalysis on its own. It was also observed that this catalyst gives out a yield that is 10 times more than the ruthenium photocatalyst. Additionally, it can also carry out reactions in red light wavelength, which is rarely seen in biohybrid catalysts. The researchers say this improved photocatalyst could be integrated into a chemical process using the two reactions tested in this study. Thiol-ene bonds are useful for making compounds used for protein imaging and sensing, drug delivery, and biomolecular stability. This photocatalyst can be used to derive good quality biofuels from plants and other materials by the process of lignin depolymerization.

All in all, this discovery has helped researchers in many ways and given out better outcomes than the existing photocatalyst.

Sources:

https://newsconcerns.com/this-light-powered-catalyst-mimics-photosynthesis/

https://www.jioforme.com/this-light-powered-catalyst-mimics-photosynthesis/923377/

https://www.sciencedaily.com/releases/2021/11/211115123534.htm

Author: Mahek Nalawade