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Microbial fuel cell (MFC) has attracted much attention in treating organic wastewater due to its double functions of degrading organics and generating electricity with microorganisms as biocatalysts. Unfortunately, some organics with biological toxicity such as acridine could inhibit the growth and activity of the microorganisms on the anode so that the double functions of MFC would recede. Enhancing microbial activity by using new biocompatible materials as anodes is prospective to solve problem. A novel anode was achieved by electrodepositing g-C 3 N 4 sheets to the carbon felt (CF) modified with polyaniline-dopamine composite film, and used to treat wastewater containing acridine for the first time. After the operation of 13 d, MFC loading with the composite anode showed a degradation efficiency of 98.3% in 150 mg L−1 acridine, while that of CF-MFC was 55.8%. Moreover, MFC loading the modified anode obtained a maximum power density of 1976 ± 47 mW m−2, 140.1% higher than that of CF-MFC. Further analysis revealed that the functional microorganisms associated with acridine degradation such as Achromobacter and Alcaligenes were enriched on the g-C 3 N 4 /PANI-DA/CF anode. Moreover, the composite anode could improve the activity of microorganisms and elicit them to generate conductive nanowires, which was beneficial to transferring electrons from microbes to anode over long distances, suggesting a promising prospect application in MFC. [Display omitted] • The carbon felt anode of MFC was modified using g–C 3 N 4 –polyaniline-dopamine. • The acridine of 150 mg L−1 could be degraded by 98.3% with MFC loading modified anode. • The power density of MFC with the modified anode was increased by 140.1%. • The modified anode could elicit microbes to generate conductive nanowires. [ABSTRACT FROM AUTHOR]

• Indole can be effectively degraded by MFC with the modified carbon felt anode. • The modified anode provided suitable environment for electroactive bacteria growth. • 90.3 % of 200 mg L−1 indole was degraded by MFC after 120 h operation. • The power density of 3184.4 mW·m−2 was achieved for MFC loading the modified anode. Indole is a high-toxic refractory nitrogen-containing compound that could cause serious harm to the human and ecosystem. It has been a challenge to develop economical and efficient technology for degrading indole. Microbial fuel cell (MFC) has great potential in the removal of organic pollutants utilizing microorganisms as catalysts to degrade organic matter into the nutrients. Herein, a novel anode of Fe 2 O 3 -polyaniline-dopamine hybrid composite modified carbon felt (Fe 2 O 3 -PDHC/CF) was prepared by electrochemical deposition. The degradation efficiency of indole by the MFC loading Fe 2 O 3 -PDHC/CF anode was up to 90.3 % in 120 h operation, while that of the MFC loading CF anode was only 44.0 %. The maximum power density of the MFC loading Fe 2 O 3 -PDHC/CF anode was 3184.4 mW·m−2, increasing 113 % compared to the MFC loading CF anode. The superior performances of the MFC with Fe 2 O 3 -PDHC surface-modified anode owned to the synergistic effect of high conductive Fe 2 O 3 and admirably biocompatible polyaniline-dopamine. MFC with the Fe 2 O 3 -PDHC/CF anode could produce considerable electricity and effectively degrade indole in water, which demonstrated a practical approach for the efficient degradation of refractory organic compounds in wastewater. [ABSTRACT FROM AUTHOR]