GO/PEDOT modified biocathode promoting CO2 reduction to CH4 in microbial electrosynthesis
Microbial electrosynthesis (MES) is a promising energy conversion technology, as it can store the intermittent renewable electricity while converting CO2 to value-added products using microorganisms as catalysts. However, for the MES of CO2 reduction to CH4, the performance is still severely limited due to primarily the poor biofilm and secondary the low loading surface area of the biocathode. Here, a novel cathode with GO/PEDOT film was fabricated by electropolymerizing conductive poly (3,4-ethylenedioxythiophene) (PEDOT) onto 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 mmol/m2/d (the highest rate reported up to now) was achieved with a Faraday efficiency > 92% at the operation potential of -0.9 V vs. Ag/AgCl, which increased by 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 the biofilm formation, but also increased the area for microbial colonization. This study demonstrates GO/PEDOT film modified carbon cloth is a promising material for the MES of CO2 reduction to CH4 and can be beneficial to the development of MES.