Improving the performance of anode is a crucial step for increasing power output of marine sediment microbial fuel cells (SMFCs). A multi‐walled carbon nanotube/polyaniline (MWCNTs/PANI) modified anode was prepared by the way of electrochemical deposition and its electrochemical performance is investigated in this paper. Result shows that the wettability of carbon felt becomes better and the number of bacteria (9.52 × 1012 m−2) on anode biofilm is increased respectively, which is 9 times higher than that of the unmodified. The anti‐polarization ability of the modified anode increases significantly and its kinetic activity of electron transfer increases 4 times. Its exchange current density is 3.62 × 10−5 A cm−2. The maximum power density of the modified SMFC reaches 527.0 mW m−2, which is 4 times higher than that of the unmodified one. Finally, a novel molecular synergistic mechanisms for the enhanced SMFC is also presented, based on the higher bacteria number, the capacitive performance of PANI, the hydrogen bond interaction and higher conductivity of MWCNTs. This excellent electrochemical performance makes the MWCNTs/PANI composite be a potential choice for higher output SMFC.

Summary Low power limits the application of microbial fuel cells (MFCs). Our research mainly focuses on the modification of the electrode and looking for new anode material for high‐power marine benthic microbial fuel cells(BMFCs). A MnO2/PPy composite‐modified anode was fabricated by in situ chemical polymerization. Surface topography and properties were characterized by scanning electron microscopy and infrared spectroscopy, respectively, indicating that the MnO2/PPy composite is of a ‘mosaic‐like’ microstructure. The electrochemical performance and wettability of different kinds of anode were investigated respectively. Cyclic voltammetry and linear sweep voltammetry tests show that MnO2/PPy composite‐modified electrode has a typical capacitance feature; its capacitance is 3.1 times higher than that of unmodified electrode. Contact angle of the composite‐modified anode reduces to 46 ± 0.5°, and its kinetic activity increased for more than 1.1 times. The maximum output power density of MnO2/PPy composite‐modified cell reached 562.7 ± 10 mW m−2, which is 2.1‐fold of the unmodified one. Finally, the composite‐modified anode provides an alternative potential choice for high‐performance cell, and the possible influence mechanism of composite materials on the BMFCs was also analyzed. Copyright © 2016 John Wiley & Sons, Ltd.

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