Optimal Geometric Parameters for 3D Electrodes in Bioelectrochemical Systems: A Systematic Approach

Carbon dioxide reduction to high-value chemicals in microbial electrosynthesis system: Biological conversion and regulation strategies

Large emissions of atmospheric carbon dioxide (CO2) are causing climatic and environmental problems. It is crucial to capture and utilize the excess CO2 through diverse methods, among which the microbial electrosynthesis (MES) system has become an attractive and promising technology to mitigate greenhouse effects while reducing CO2 to high-value chemicals. However, the biological conversion and metabolic pathways through microbial catalysis have not been clearly elucidated. This review first introduces the main acetogenic bacteria for CO2 reduction and extracellular electron transfer mechanisms in MES. It then intensively analyzes the CO2 bioconversion pathways and carbon chain elongation processes in MES, together with energy supply and utilization. The factors affecting MES performance, including physical, chemical, and biological aspects, are summarized, and the strategies to promote and regulate bioconversion in MES are explored. Finally, challenges and perspectives concerning microbial electrochemical carbon sequestration are proposed, and suggestions for future research are also provided. This review provides theoretical foundation and technical support for further development and industrial application of MES for CO2 reduction.

A Comprehensive Modeling Analysis of Formate-Mediated Microbial Electrosynthesis*

Mediated microbial electrosynthesis (MES) represents a promising strategy for the capture and conversion of CO₂ into carbon-based products. We describe the development and application of a comprehensive multiphysics model to analyze a formate-mediated MES reactor. The model shows that this system can achieve a biomass productivity of ∼1.7 g L^-1  h^-1 but is limited by a competitive trade-off between O₂ gas/liquid mass transfer and CO₂ transport to the cathode. Synthetic metabolic strategies are evaluated for formatotrophic growth, which can enable an energy efficiency of ∼21 %, a 30 % improvement over the Calvin cycle. However, carbon utilization efficiency is only ∼10 % in the best cases due to a futile CO₂ cycle, so gas recycling will be necessary for greater efficiency. Finally, separating electrochemical and microbial processes into separate reactors enables a higher biomass productivity of ∼2.4 g L^-1  h^-1 . The mediated MES model and analysis presented here can guide process design for conversion of CO₂ into renewable chemical feedstocks.