Scientists have found a way to mimic nature’s own process of reducing carbon dioxide in the atmosphere — photosynthesis — to capture excess atmospheric carbon dioxide. This artificial photosynthesis harnesses solar energy and converts the captured carbon dioxide into carbon monoxide, which can be processed to make fuels.
Scientists from Jawaharlal Nehru Centre for Advanced Scientific Research, an institute of the Department of Science and Technology, designed and fabricated an integrated catalytic system based on a metal-organic framework (MOF-808) comprising a ‘photosensitiser’ to harness solar power and a catalytic centre to reduce carbon dioxide.
MOFs are compounds of metal ions and organic molecules that form a cage- or sponge-like structure, in which other molecules can be stored. ‘Photosensitisers’ absorb energy from light and transfer it to a nearby molecule.
The scientists have immobilised a photosensitiser — a chemical called ruthenium bipyridyl complex [Ru(bpy)2Cl2] — and a catalytic part — rhenium carbonyl complex [Re(CO)5Cl] — inside the nano-space of a metal-organic framework for artificial photosynthesis. The close proximity of these molecular entitiesin the confined nano-space results in good carbon dioxide uptake.
The catalyst exhibited visible-light-driven reduction of carbon dioxide to carbon monoxide, with more than 99 per cent selectivity. The catalyst also oxidises water to produce oxygen.