In-situ growth of graphene/polyaniline for synergistic improvement of extracellular electron transfer in bioelectrochemical systems

Graphene composite has been widely used in various bioelectrochemical systems (BES). However, it is suffered from tedious fabrication procedure and ambiguous mechanism for its effect on BES. Here, a one-step and in-situ strategy for simultaneously graphene exfoliation and aniline polymerization was developed for fabrication of graphene/PANI composite electrode (GO/PANIOS). This GO/PANIOS outperformed graphite paper (GP), GP with PANI (GP/PANI) and GP with electrochemical exfoliated graphene (GOH2SO4) in Shewanella oneidensis MR-1 inoculated BES (improved the power density output, i.e., 24, 3.4 and 5.7 times of GP , GP/PANI and GOH2SO4, respectively). Further analysis revealed a synergistic improvement on both direct and mediated extracellular electron transfer of S. oneidensis MR-1 by GO/PANIOS contributed to its performance enhancement in BES. This work not only provided a simple strategy for graphene composite fabrication, but also unveiled the underlying mechanism for its stimulation on BES, which promises new opportunity of graphene composite application in various biosystems.