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Abstract Electron transfer efficiency in electroactive biofilm is the limiting factor for bioelectricity output of bioelectrochemical system. Here, carbon felt (CF) is coated with manganese dioxide (MnO 2) which acts as electron mediator in electroactive biofilm. A wrapping layer of conducting Poly 3,4-ethylenedioxythiophene is developed to protect the MnO 2 and enhance electron transfer efficiency of MnO 2 mediator. The hybrid bioanode (PEDOT/MnO 2 /CF bioanode) delivered the highest electron transfer efficiency (6.3 × 10−9 mol cm−2 s−1/2) and the highest capacitance of 4.78 F, much higher than bare CF bioanode (1.50 ± 0.04 × 10−9 mol cm−2 s−1/2 and 0.42 F). As a result, microbial fuel cells could produce a maximum power density of 1534 ± 13 mW m−2, approximately 57.7% higher than that with the bare carbon felt anode (972 ± 21 mW m−2). Possible mechanisms are proposed to help understanding the different function of the PEDOT and MnO 2 on the anodic layer. This study introduces an effective method for the fabrication of high performance anode. Graphical abstract Unlabelled Image Highlights • A MnO 2 layer acts as electron mediator in electrochemical biofilm. • The wrapping layer of PEDOT helps to enhance electron transfer efficiency. • Electron transfer efficiency improved by ~4 times. • PEDOT/MnO 2 /CF anode increases the maximum power density by 143%. [ABSTRACT FROM AUTHOR]