A Graphene/Poly(3,4-ethylenedioxythiophene) Hybrid as an Anode for High-Performance Microbial Fuel Cells

A microbial fuel cell (MFC) is an innovative power-output device, which utilizes microorganisms to metabolize fuel and transfers electrons to the electrode surface. In this study, we decorated the surface of graphene (G) with a conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), through galvanostatic electropolymerization to fabricate a G/PEDOT hybrid anode for an Escherichia coli MFC. Cyclic voltammetry and electrochemical impedance spectroscopy analyses illustrated that the G/PEDOT hybrid anode possesses a larger active surface area and lower charge-transfer resistance than three other kinds of anodes, namely, carbon paper (CP), graphene-modified carbon paper (CP/G), and PEDOT-modified carbon paper (CP/PEDOT). Scanning electron microscopy was used to investigate the bacteria growth on the four anodes. A compact biofilm was formed on the hybrid anode owing to the electrostatic interaction between the negatively charged bacteria and positively charged PEDOT backbone. The constant-load (1 KΩ) discharge curves of MFCs with CP, CP/G, CP/PEDOT, and G/PEDOT anodes revealed that the G/PEDOT electrode had good stability and high voltage output. The G/PEDOT anode generated a maximum power density of 873 mW m^-2 , which is about 15 times higher than that of CP (55 mW m^-2 ) in an H-shaped dual-chamber MFC. All the experimental results suggest that the performance of the G/PEDOT hybrid anode is superior to the CP, CP/G, or CP/PEDOT anode.