Hollow cobalt ferrite nanofibers integrating with carbon nanotubes as microbial fuel cell anode for boosting extracellular electron transfer

Currently, the commercial applications of MFCs are mainly constricted by the relatively lower power density derived from poor electroactive bacteria (EAB) adhesion and sluggish extracellular electron transfer (EET) at the anode interface. To address this issue, herein, hollow cobalt ferrite nanofibers integrating with carbon nanotubes (CoFe2O4/CNTs) are fabricated as an efficient anode electrocatalyst via simple electrospinning, pyrolysis, and in -situ hybrid process. Interestingly, the CoFe2O4/CNTs electrocatalysts with a continuously interconnected network not only strengthen the interfacial affinity with EAB but also promote the electron transfer efficiency between the anode and EAB, which endows the MFCs with a maximum power density of 2290 mW m- 2, far exceeding the referential CoFe2O4 (1458 mW m-2) and carbon cloth (496.7 mW m-2) anode. The outstanding power density can be attributed to the continuous porous scaffold, remarkable electrocatalytic activity toward the redox reactions in the biofilm, and positively charged cations with multiple valence states on the CoFe2O4/ CNTs electrocatalyst, favoring the negatively charged Geobacter adhesion, colonization, and mediating long-distance EET across the thick biofilm. This research provides a new strategy for fabricating anode electro-catalysts to improve the overall MFCs performance.