Framework of Cytochrome/Vitamin B2 Linker/Graphene for Robust Microbial Electricity Generation.

A bioelectrochemical system (BES) allows direct electricity production from wastes, but its low-power density, which is mainly associated with its poor anodic performance, limits its practical applications. Here, the anodic performance of a BES can be significantly improved by electrodepositing vitamin B2 (VB2) onto a graphene [reduced graphene oxide (rGO)]-modified glassy carbon electrode (VB2/rGO/GC) with Geobacter sulfurreducens as the model microorganisms. The VB2/rGO/GC electrode results in 200% higher electrochemical activity than a bare GC anode. Additionally, in microbial electrolysis cells, the current density of this composite electrode peaks at ∼210 μA cm-2 after 118 h and is maintained for 113 h. An electrochemical analysis coupled with molecular simulations reveals that using VB2 as a linker between the electrochemically active protein of this model strain and the rGO surface accelerates the electron transfer, which further improves the bioelectricity generation and favors the long-term stability of the BES. The VB2 bound with a flexible ribityl group as the organic molecular bridge efficiently mediates energy conversion in microbial metabolism and artificial electronics. This work provides a straightforward and effective route to significantly enhance the bioenergy generation in a BES.