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

Semi-biological photosynthesis utilizes the unique ability of microbial catalysts together with synthetic photosensitizers (semiconductors) to produce high-value chemicals from sustainable feedstocks. In this work, we devise a semi-biological hybrid system consisting of sustainable photosensitizers, carbon dots in the size range of 5–35 nm (CDs) interfaced with bacteria, Geobacter sulfurreducens, to reduce fumarate to succinate as a model hydrogenation reaction. After 7 days of solar irradiation, using quantitative proton nuclear magnetic resonance spectroscopy (qNMR), the CD−G. sulfurreducens photosystem produced ∼18 mM of succinate without the need for a redox mediator. Moreover, in reusing the CDs, ∼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.