Straw-derived macroporous biochar as high-performance anode in microbial fuel cells

Large-scale application of MFCs is limited by the high cost of electrode and low power density. In this study, the electrochemical structure and power output performance of three novel straw-derived biochar are discussed and characterized by scanning electron microscope, specific surface area, cyclic voltammetry, Raman spectrum, electrochemical impedance spectroscopy etc. Compared with the common carbon felt electrode, the optimal electricity generation ability and electrochemical affinity are obtained in corn straw biochar electrode: the rough surface with macroporous structure and high degree of graphitization facilitates the attachment of electroactive bacteria; the maximum output voltage, open circuit voltage, power density and coulombic efficiency reach 662.64±4.03 mV, 798.24±3.65 mV, 1.54±0.18 W m-2 and 50.39±1.68%, respectively; the maximum COD removal efficiency of 77.45±1.69% is achieved; exchange current density (4.6142×10-4 A cm-2) in corn straw electrode presents the better electrochemical activity than that of carbon felt electrode. These implies that corn straw-derived biochar is a competitive raw material for MFC anode.