All-in-one electro-microbial system for solar-powered CO2 fixation into succinate

The requirement for multiple reactors is a key factor limiting the viability of electro-microbial tandem CO2 fixation. Selective single-reactor electro-microbial synthesis of C4 compounds from CO2 remains a major challenge. To this end, we develop an all-in-one electro-microbial system that enables selective CO2-to-succinate fixation by leveraging two different microbial species that can tandemly operate in opposite chambers of a single electrochemical reactor. A key component here is the installation of an anion exchange membrane to not only mediate the transport of acetate intermediates but also give rise to separated anaerobic and aerobic environments that promote the function of two separate microbial species. The optimized system enables sustainable CO2-to-succinate conversion over 15 days, achieving a production rate of 33.8 mg L⁻1 day⁻1 and a final titer of high-purity succinate exceeding 0.5 g L⁻1, with life cycle analyses indicating net-negative carbon emissions. As a proof-concept we further demonstrate that this system can continually produce succinate when simply powered through a photovoltaic device, with an average solar-to-succinate efficiency of 0.75%, showing promise for decentralized operation.