Enhanced performance of microbial fuel cell with in situ preparing dual graphene modified bioelectrode

•A three-step method was built to prepare dual graphene modified bioelectrode.•3D graphene/biofilm architectures were formed in graphene modified bioelectrode.•The viability/thickness of microbial biofilm decreased in graphene bioelectrode.•Electrochemical performance of graphene modified MFC was significantly enhanced.•Mechanisms of EET process and implication of graphene modified MFC were proposed.

This study proposed a three-step method to prepare dual graphene modified bioelectrode (D-GM-BE) by in situ microbial-induced reduction of GO and polarity reversion in microbial fuel cell (MFC). Both graphene modified bioanode (GM-BA) and biocathode (GM-BC) were of 3D graphene/biofilm architectures; the viability and thickness of microbial biofilm decreased compared with control bioelectrode (C-BE). The coulombic efficiency (CE) of GM-BA was 2.1 times of the control bioanode (C-BA), which demonstrated higher rate of substrates oxidation; the relationship between peak current and scan rates data meant that GM-BC was of higher efficiency of catalyzing oxygen reduction than the control biocathode (C-BC). The maximum power density obtained in D-GM-BE MFC was 122.4 ± 6.9 mW m−2, the interfacial charge transfer resistance of GM-BA and GM-BC were decreased by 79% and 75.7%. The excellent electrochemical performance of D-GM-BE MFC was attributed to the enhanced extracellular electron transfer (EET) process and catalyzing oxygen reduction.

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