Hybrid Conducting Biofilm with Built-in Bacteria for High-Performance Microbial Fuel Cells

Efficiently transporting extracellular electrons from microbial biofilms to the electrodes is challenging and critical in achieving high-performance microbial fuel cells (MFCs). In this work, we develop a simple and effective method to fabricate hybrid electroactive biofilms by inserting bacteria into graphene–carbon-nanotube (G–CNT) networks (namely, G–CNT-biofilm) as an anode for MFCs. This novel architecture greatly enhances direct extracellular electron transfer between Shewanella oneidensis and the electrode, due to strong adhesion of the hybrid conducting biofilm onto the anode surface, as well as the large surface area of graphene and the high conductivity of CNTs. A current density of 120 μA cm−2 and a maximum power density of 97.9 μW cm−2 are obtained in the MFC with the hybrid biofilm anode, which is significantly higher than those of a naturally growing biofilm anode (20 μA cm−2 and 6.5 μW cm−2).