Fig. 1

a MFC-coated and MFC-uncoated were incubated for 600 h of output voltage, and the anode medium was replaced when the output voltage droped. b Polarization curve and power density curve when the output voltage of the reaches its maximum value. c Nyquist plots from electrochemical impedance spectroscopy measurements of MFC-coated (black empty circle) and MFC-uncoated (red empty circle) scanned at 0.1 ~ 100 kHz at open-circuit potential (the inset on the right is the charge transfer resistance in the high frequency region of MFC-uncoated). d Cyclic voltammograms curve of coated-MFC and uncoated-MFC