En route to artificial photosynthesis: the role of polyoxometalate based photocatalysts

Abstract

As a consequence of increasing global energy demand and depleting fossil fuels, artificial photosynthesis, i.e., subsequent photocatalytic water oxidation and CO₂ reduction, has become significant for providing renewable energy resources. To construct an ideal artificial photosynthetic system, three components are essential: photosensitizer, water oxidation catalyst, and CO₂ reduction catalyst. As assembling these three components in a single integrated device is extremely difficult, an alternative strategy is to divide the overall process into two half-reactions: water oxidation and CO₂ reduction. Once each half-cell reaction is well-understood and optimized, these two reactions can be coupled in a single integrated device to convert solar energy efficiently. The structural diversity and tunable redox properties of polyoxometalates (POMs) connect these strategies, like “killing two birds with one stone” to save the environment and fulfill future energy demands. This highlight focuses on the active role of POMs in reducing the activation energy barrier and sluggish reaction dynamics in carrying out the artificial photosynthesis process. The photochemical and catalytic properties of POMs in separate water oxidation, CO₂ reduction, and CO₂ reduction coupled with water oxidation have been outlined.