Recent advances in innovative electrode and reactor designs for microbial electrochemical CO₂ conversion

Microbial electrosynthesis (MES) enables electricity-driven conversion of CO₂ into fuels, chemicals, and materials, but its scalability remains limited by low productivity and energy efficiency. While recent reviews have focused on cathode materials and bioelectrocatalytic mechanisms, the influence of structural configuration on electron transfer, gas retention, and process integration has received less systematic attention. This review highlights recent advances in configuration-driven cathode and reactor designs that reshape electrochemical-biological coupling. We discuss multifunctional and dual-layer cathodes, volumetric and flow-electrode concepts, zero-gap systems, electrolytic gas-lift bubble columns, integrated reaction-separation strategies, and electrochemical-biological hybrid platforms. These approaches enhance electron utilization, improve gas–liquid mass transfer, and support higher product titers. By emphasizing structural and functional integration rather than material substitution, this review provides a design-oriented perspective for advancing MES toward scalable and economically viable CO₂ valorization.