Anode modification by electrochemical oxidation: A new practical method to improve the performance of microbial fuel cells

Electrochemical oxidation as a convenient and effective method was established for anode modification to improve the performance of microbial fuel cells (MFCs). The anode modification was realized by one-step electrochemical treatment in one of the three electrolytes (nitric acid, ammonium nitrate, ammonium persulfate) at ambient temperature. The performances of MFCs before and after anode modification were compared, confirming that all these anode modifications posed positive effects. The maximum power density of the MFC with the anode modified by nitric acid was 792 mW/m2, which was 43% larger than the unmodified control (552 mW/m2). Furthermore, the Coulombic efficiency (CE) significantly promoted about 71% from 14% (the unmodified MFC) to 24%. It revealed that the electrochemical oxidation resulted in the change of the anode properties, such as surface morphology, internal resistance and anode potential, and thus benefited to the microbial attachment and electron transfer on the anode surface, which might contribute to the performance improvement of the MFCs.

► Anode electrochemical modification was convenient and effective to improve MFCs performance.
► Three modifications posed positive effects, and CM-N was the best with power density increase by 43%.
► Electrochemical oxidation resulted in the change of anode properties and surface characteristics.
► Increasing surface area and current response might contribute to the performance improvement.