GO/PEDOT modified biocathodes promoting CO2 reduction to CH4 in microbial electrosynthesis

Abstract

Microbial electrosynthesis (MES) is a promising energy conversion technology as it can store intermittent renewable electricity while converting CO₂ to value-added products using microorganisms as catalysts. However, the performance of CH₄-producing MES is severely limited by the poor biofilm formation and the low loading surface area of biocathodes. Here, a novel cathode with a GO/PEDOT film was fabricated by electropolymerizing conductive poly (3,4-ethylenedioxythiophene) (PEDOT) on graphene oxide (GO) film modified carbon cloth. The GO/PEDOT modified electrode was applied to the MES of CO₂ reduction to CH₄, and a maximum CH₄ production rate of 315.3 ± 13.2 mmol per m² per day (7.06 ± 0.3 l per m² per day) (the highest rate reported up to now at −0.9 V vs. Ag/AgCl) was achieved with a Faraday efficiency > 92% at an operating potential of −0.9 V vs. Ag/AgCl, which increased 3.9-fold in contrast to the bare carbon cloth cathode. Electrochemical analysis, scanning electron microscopy, and phylogenetic analyses of microbial communities indicated that the GO/PEDOT film not only improved biofilm formation, but also increased the area for microbial colonization. This study demonstrates that GO/PEDOT film modified carbon cloth is a promising material for biocathodes of CH₄-producing MES and can be beneficial to the development of MES.