Enhanced electricity generation and extracellular electron transfer by polydopamine–reduced graphene oxide (PDA–rGO) modification for high-performance anode in microbial fuel cell

Anode performance is a key factor for power output and long-term stability of microbial fuel cells (MFCs). This is because it considerably influences biofilm growth and extracellular electron transfer (EET). In this study, carbon cloth (CC) was used as the anode substrate, and a hydrophilic, biocompatible, and highly conductive CC–PDA–rGO anode was synthesized by surface modification with polydopamine (PDA) and reduced graphene oxide (rGO) using an easy and facile solvent immersion method. The power density of the MFC with CC–PDA–rGO anode reached 2047 mW·m−2, which was 6.1, 2.2, and 1.9 times greater than those of the CC, CC–PDA, and CC–rGO, respectively. The charge transfer resistance of the MFC prepared with the CC–PDA–rGO anode was ten-fold lower than that of the CC anode. Moreover, the EET was remarkably enhanced on the CC–PDA–rGO anode, and the electroactive biofilm of CC–PDA–rGO anode exhibited the highest cell viability. The CC–PDA–rGO anode achieved the highest cumulative total charge, which suggested that it had the best electron harvesting capacity. The foregoing can be attributed to the introduction of PDA and rGO onto the electrode surface. The PDA possesses superior hydrophilicity and excellent adhesive force for strong interaction with biofilm, whereas the rGO provides abundant electrochemically active sites to facilitate electron transfer from the biofilm to the anode. This work provides an easy and facile surface modification method for the development of high-performance MFC anode materials.