Spatially Decoupled Electro‐Biosystem for Efficient CO2‐to‐Chemicals Conversion via Tandem Catalysis

Abstract The upcycling of carbon dioxide (CO 2 ) into value‐added chemicals offers a compelling strategy for sustainable carbon utilization. However, the efficient synthesis of energy‐dense, long‐chain molecules remains a significant challenge. Here, a spatially decoupled electro‐biosystem integrating CO 2 electrolysis with microbial fermentation is presented to produce high‐value chemicals. A catalytic platform using tannic acid‐Cu 2+ metal‐phenolic networks is developed to spatially confine the synthesis of Ag and Cu 2 O nanoparticles within a covalent‐organic polymer, creating tandem catalytic sites. This design significantly enhances CO 2 ‐to‐ethanol selectivity (Faradaic efficiency: 44.5%) and boosts current density to 400 mA cm −2 . A compact membrane electrode assembly reactor (5×5 cm 2 ) enables ethanol production in pure water, which is further converted by engineered Escherichia coli into itaconic acid, isopropanol, and polyhydroxybutyrate. The modular design optimizes electrochemical reduction and microbial bioconversion, reducing metabolic burdens and improving efficiency, offering a scalable, adaptable biohybrid platform for CO 2 valorization.