Electro-Bio Conversion for Renewable Materials, Fuels and Chemicals

Recent breakthroughs highlighted the possibility to substantially improve CO₂ conversion rate and efficiency via integrating ectrocatalytic CO₂RR (CO₂ reduction reaction) to C2+ intermediates and bioconversion to diverse products. Traditional electrocatalytic CO₂RR can achieve high efficiency, yet is limited in product profile, producing primarily C1 or C2 products. Integrating catalytic CO₂ reduction with bioconversion could substantially advance the product profile to produce chemicals, fuels, materials, and food to replace the current petrochemical and agriculture products. The new electro-bio systems could substantially improve the solar-to-product efficiency, advance carbon capture and utilization, and mitigate climate change. However, the state-of-the-art electro-bio systems are limited by inefficient electron and mass transfers, unfavorable metabolic kinetics, and inadequate molecular building blocks. We overcome these barriers with the systematic design of electrocatalysis, the chem-bio interface, and microorganisms to enable efficient electro-microbial conversion with C2 (EMC2) intermediates. The soluble C2 intermediates can facilitate rapid mass transfer, readily enter primary metabolism, have less toxicity, carry more energy and electrons, and serve as better molecular building blocks for many microorganisms. Despite the advantages, the integration of chemical and biological conversions must overcome the intermediate incompatibility, the harsh chemical catalysis conditions, and the inefficient mass, energy, and electron transfers. On one hand, we have designed the electrolytes, electrode, electrolyzer, and catalyst configurations to allow efficient CO₂RR into acetate and ethanol at conditions compatible to biological conversion. On the other hand, we hereby carried out multi-module cellular design to enhance bioproductivity, facilitate efficient substrate usage, and improve reductant production. Furthermore, the systematic design achieved integrated, continuous, and rapid microbial biomass and PHA production from CO2 with record-level productivity. The multi-layer EMC2 design has achieved 6 and 8 times increase of microbial biomass productivity compared to C1 intermediate and hydrogen-driven routes, respectively. Moreover, the systematic design achieved integrated, continuous, and rapid microbial biomass and PHA production from CO2 with record-level productivity. Overall, the EMC2 system could achieve 4.5% solar-energy-driven CO₂ conversion to biomass, which is multiple times higher than the natural photosynthesis. Further electrocatalytic and microbial design has enabled novel routes for the efficient conversion of CO₂ into various food, chemicals, and fuels.