Viologen derivative-induced graphene hybrid biofilms for high-performance microbial fuel cells

The development of high-quality hybrid biofilms is essential for the performance improvement of microbial fuel cells (MFCs). Here, a novel graphene hybrid biofilm has been developed for MFCs by utilizing a positive-charged viologen derivative (4,4′-(thiazole[5,4-d]thiazol-2,5-diyl)bis(1-(4-nitrobenzyl)pyridine-1-ium)dichloro) as dual-functional component. Before the reduction of graphene oxide by bacterial cells, the viologen derivative can improve binding efficiency between negative-charged bacterial cells and graphene oxide due to electrostatic interaction, leading to an increased cell density in graphene hybrid biofilm. In addition to the effective direct electron transfer network provided by graphene nanosheets, the viologen derivative can serve as an electron mediator for building extra indirect electron transfer pathway. Benefiting from these advantages, this graphene hybrid biofilm is far superior to traditional bacterial cells-attached bioanode when applying in MFCs. This work exploits a simple but feasible strategy to upgrade cell density and electron transfer efficiency of hybrid biofilm, which would deepen the application of artificial biofilm in bioelectrochemical systems.