Semi–biological photosystem: Harnessing carbon dots and Geobacter sulfurreducens for solar–driven hydrogenation

Semi–biological photosynthesis utilises the unique ability of microbial catalysts together with synthetic photosensitisers (semiconductors) to produce high–value chemicals from sustainable feedstocks. In this work, we devise a semi–biological hybrid system consisting of sustainable photosensitisers, carbon dots in the size range of 5 nm − 35 nm (CDs) interfaced with bacteria, Geobacter sulfurreducens (G. sulfurreducens) to reduce fumarate to succinate as a model hydrogenation reaction. After seven days of solar irradiation, using quantitative proton nuclear magnetic resonance spectroscopy (qNMR), the CD–G. sulfurreducens photosystem produced approximately 18 mM of succinate without the need for a redox mediator. Moreover, in reusing the CDs approximately 70% of the succinate (compared to the previous cycle) was recovered. The proposed photobiohybrid system paves a new avenue for sustainable solar–to–chemical conversion in high–value chemical production.