Bioelectrochemical reduction of CO₂ into formic acid using Escherichia coli whole-cell biocatalyst

Rising atmospheric carbon dioxide (CO₂) levels prompt concern for climate change, urging the immediate development of sustainable technologies to convert CO₂ into valuable products. This study focused on developing a biocathode for bioelectrochemical CO₂ reduction, utilizing Escherichia coli. The performance of the biocatalyst was assessed by varying wet cell mass from 0.0125 to 0.075 g/cm² under different operational conditions, including electrode potential (− 250 to − 1250 mV vs. Ag/AgCl) and methylene blue use as a mediator for electron transfer between electrode and microbial cells. Through optimization, the system achieved enhanced CO₂ conversion rates and improved product selectivity. Beyond 50 h extended electrolysis period, consistent formic acid formation was observed with the highest Faradaic efficiency at 40 h reaction time. Produced formic acid shows a maximum concentration of 23.35 mM and a maximum Faradaic efficiency of 22.78% at − 750 mV vs. Ag/AgCl, using 0.05 g/cm² of wet cells. These findings hold significant promise for advancing technologies dedicated to CO₂ sequestration and generating value-added products from CO₂.