Biocompatible and capacitive PDA-Ov-Co3O4@CC anode augmented exoelectrogens enrichment and extracellular electron transfer in microbial fuel cells

Metal oxides rich in oxygen vacancies (O v ) possess excellent intrinsic conductivity, variable valence metal center and high capacitance, which were potential candidates as microbial fuel cells anode. However, their high bacterial toxicity greatly hindered the activity of biofilm. To solve this issue, in this work, polydopamine (PDA) covered capacitive O v doped Co 3 O 4 nanosheets were designed and successfully grown on carbon cloth (CC). The introduction of O v significantly promoted the charge storage, the net charge and the accumulated charge were 217.1 and 2680.3 C/m 2 , respectively, surpassed Co 3 O 4 anode without O v . In addition, O v also decreased the charge-transfer resistance ( R ct ), effectively accelerating EET. The R ct of PDA/O v -Co 3 O 4 @CC was 29.51 Ω, lower than CC (382.10 Ω). The cover of PDA prevented the direct contact between metal ions and microorganisms, greatly enhanced the bacterial viability. The power density of MFCs with PDA/O v -Co 3 O 4 @CC anode was 2.77 W/m 2 , 1.45 times higher than that of bare CC (1.90 W/m 2 ). In addition, PDA/O v -Co 3 O 4 @CC anode displayed excellent coulombic efficiency and daily COD removal amount (23.5 % and 147.6 mg/L/d), higher than the control groups. The community analysis showed the abundance of Geobacter on PDA/O v -Co 3 O 4 @CC anode was 91 %, higher than other anodes. Present study developed a facile and effective PDA coating strategy to simultaneously enhance the biocompatibility and capacitance of O v -rich metal oxides, which will be a promising method for the preparation of high performance MFCs anode.