Recent advances in biocathode materials and configurations for reactor applications in microbial electrosynthesis of...

Elevated atmospheric carbon dioxide (CO₂) levels driven by urbanization and anthropogenic activities have accelerated global warming. CO₂ upcycling using microbial electrosynthesis (MES) offers a unique opportunity to address this critical issue. The emerging field of MES is a sustainable approach toward transforming CO₂ into resourceful chemicals because of the self-sustaining activity of electroactive bacteria (EAB). On the other hand, microbe-electrode interface engineering at the biocathode is critical for effective CO₂ conversion. The applied potential at the biocathode supplies the necessary reducing energy to the EABs for CO₂ conversion through various metabolic pathways. Various biocathode materials and configurations have been explored to enhance bioelectrochemical interactions, facilitate extracellular electron transfer in electroactive biofilms, accelerate biofilm formation, and improve CO₂ conversion efficiency. This review summarizes the studies on biocathode development in MES systems, with a focus on improving the production rates, operational stability, scalability, and faradaic efficiency for electromicrobial CO₂ conversion. A range of electrode materials and biocathode configurations is reviewed for their potential to enhance CO₂ conversion in MES. The outlook and perspectives for future research on biocathode development toward the commercialization of MES systems for CO₂ utilization are also highlighted.