Cascade synthesis of ethanol and acetate via microbial fermentation of syngas produced photoelectrochemically by molecular catalysts on BiVO4-perovskite tandem artificial leaf

ended

The photoelectrochemical conversion of the greenhouse gas carbon dioxide (CO2) to energy-rich chemicals and fuels is an attractive strategy towards climate change remediation and a circular carbon economy. However, the renewable synthesis of complex organic molecules using solar power still faces several challenges for practical application. Current synthetic systems, which can reach high light absorption and charge separation efficiencies, still rely on the use of expensive materials with improvable specificity for the generated products. On the other hand, biological systems such as microbes are far superior performing complex catalytic chemistry (C-C coupling, multi-electron catalysis) with high product specificity. The synergistic combination of synthetic and biological components enables novel synthesis pathways, otherwise inaccessible abiotically, to generate useful chemicals and fuels with higher efficiency and product specificity. The proposed project aims to build a proof-of-concept microbial hybrid artificial leaf to generate ethanol and acetate via fermentation of hydrogen and carbon monoxide (syngas) produced by molecular catalysts immobilized on an artificial leaf. The molecular catalysts will be embedded in a highly porous carbon-based cathode to generate the syngas from aqueous CO2 to feed locally the bacterium Clostridium ljungdahlii within the pores, a novel approach compared to current decoupled microbial hybrid systems. The proposed artificial leaf will integrate state-of-the-art BiVO4 and perovskite components, for efficient light absorption, charge separation and water oxidation, with the cathode. This microbial leaf will be the first example of cascade catalysis where molecular catalysts and microbes will work together to produce multi-carbon products, enabling the study of abiotic-biotic interfaces key to design new materials for improved solar (bio)chemicals generation.