Different modified multi-walled carbon nanotube–based anodes to improve the performance of microbial fuel cells

To clearly illustrate the activity effect of multi-walled carbon nanotubes (MWCNTs) and their functionality on anodic exoelectrogen in microbial fuel cells (MFCs), the growth of E. coli and anode biofilm on MWCNT-, MWCNT–COOH– and MWCNT–NH₂– modified anodes were compared with a bare carbon cloth anode. The activity effect was characterized by the amount of colony-forming units (CFUs), activity biomass, morphology of biofilms and cyclic voltammetric (CV). The results showed that MWCNTs, MWCNT-COOH and MWCNT-NH₂ exhibited good biocompatibility on exoelectrogenic bacteria. The performance of MFCs were improved through the introduction of MWCNT-modified anodes, especially in the presence of –COOH/–NH₂ groups. The MFCs with the MWCNT–COOH–modified anode achieved a maximum power density of 560.40 mW/m², which was 49% higher than that obtained with pure carbon cloth. In conclusion, the positive effects of MWCNTs and their functionality were evaluated for promoting biofilm formation, biodegradation and electron transfer on anodes. Specifically, the MWCNT–COOH–modified anode demonstrated the largest application potential for the development of MFCs.