Solar-Powered Organic Semiconductor-Bacteria Biohybrids for CO2 Reduction into Acetic Acid

An organic semiconductor-bacteria biohybrid photosynthetic system is used to efficiently realize CO2 reduction to produce acetic acid with the non-photosynthetic bacteria Moorella thermoacetica. Perylene diimide derivative (PDI) and poly(fluorene-co-phenylene) (PFP) were coated on the bacteria surface as photosensitizers to form a p-n heterojunction (PFP/PDI) layer, affording higher hole/electron separation efficiency. The pi-conjugated semiconductors possess excellent light-harvesting ability and biocompatibility, and the cationic side chains of organic semiconductors could intercalate into cell membranes, ensuring efficient electron transfer to bacteria. Moorella thermoacetica can thus harvest photoexcited electrons from the PFP/PDI heterojunction, driving the Wood-Ljungdahl pathway to synthesize acetic acid from CO2 under illumination. The efficiency of this organic biohybrid is about 1.6 %, which is comparable to those of reported inorganic biohybrid systems.