Bacteria–photocatalyst sheet for sustainable carbon dioxide utilization

The clean conversion of carbon dioxide and water to a single multicarbon product and O 2 using sunlight via photocatalysis without the assistance of organic additives or electricity remains an unresolved challenge. Here we report a bio-abiotic hybrid system with the non-photosynthetic, CO 2 -fixing acetogenic bacterium Sporomusa ovata grown on a scalable and cost-effective photocatalyst sheet consisting of a pair of particulate semiconductors (La and Rh co-doped SrTiO 3 (SrTiO 3 :La,Rh) and Mo-doped BiVO 4 (BiVO 4 :Mo)). The biohybrid effectively produces acetate (CH 3 COO – ) and oxygen (O 2 ) using only sunlight, CO 2 and H 2 O, achieving a solar-to-acetate conversion efficiency of 0.7% at ambient conditions (298 K, 1 atm). The photocatalyst sheet oxidizes water to O 2 and provides electrons and hydrogen (H 2 ) to S. ovata for the selective synthesis of CH 3 COO – from CO 2 . To demonstrate utility in a closed carbon cycle, the solar-generated acetate was used directly as feedstock in a bioelectrochemical system for electricity generation. These semi-biological approaches thus offer a promising strategy for sustainably and cleanly fixing CO 2 and closing the carbon cycle. Conversion of CO 2 to fuels or chemicals via artificial photosynthesis usually requires the assistance of organic additives or electricity. Now, a biohybrid system is reported consisting of a photocatalyst sheet and bacteria producing acetate and O 2 from CO 2 and H 2 O using sunlight as the sole energy input.