Nickel ferrite/MXene-coated carbon felt anodes for enhanced microbial fuel cell performance.

In recent years, the modification of electrode materials for enhancing the power generation of microbial fuel cells (MFCs) has attracted considerable attention. In this study, a conventional carbon felt (CF) electrode was modified by NiFe2O4 (NiFe2O4@CF), MXene (MXene@CF), and NiFe2O4-MXene (NiFe2O4-MXene@CF) using facile dip-and-dry and hydrothermal methods. In these modified CF electrodes, the electrochemical performance considerably improved, while the highest power density (1385 mW/m2), which was 5.6, 2.8, and 1.4 times higher than those of CF, NiFe2O4@CF, and MXene@CF anodes, respectively, was achieved using NiFe2O4-MXene@CF. Furthermore, electrochemical impedance spectroscopy and cyclic voltammetry results confirmed the superior bioelectrochemical activity of a NiFe2O4-MXene@CF anode in a MFC. The improved performance could be attributed to the low charge transfer resistance, high conductivity and number of catalytically active sites of the NiFe2O4-MXene@CF anode. Microbial community analysis demonstrated the relative abundance of electroactive bacteria on a NiFe2O4-MXene@CF anodic biofilm rather than CF, MXene@CF, and NiFe2O4@CF anodes. Therefore, these results suggest that combining the favorable properties of composite materials such as NiFe2O4-MXene@CF anodes can open up new directions for fabricating novel electrodes for renewable energy-related applications.

MnCo2O4 coated carbon felt anode for enhanced microbial fuel cell performance.

A highly efficient anode is very crucial for an improved microbial fuel cell (MFC) performance. In this study, a binder-free manganese cobalt oxide (MnCo2O4@CF) anode was synthesized using a conventional carbon felt (CF) by a facile hydrothermal method. A large electrochemically active and rough electrode surface area of MnCo2O4@CF anode improved the substrate fluxes and microbial adhesion/growth. Furthermore, the electrochemical tests on the synthesized anode confirmed the superior bioelectrochemical activity, reduced ion transfer resistance, and excellent capacitance. This resulted in an improved power density (945 mW/m2), which was 3.8 times higher than that of CF anode. The variable valence state, high stability and biocompatibility of MnCo2O4@CF resulted in continuous current density performance for five MFC cycles. High-throughput biofilm analysis revealed the enrichment of electricity producing phylum of Proteobacteria and Bacteroidetes (∼90.0%), which signified that the modified MnCo2O4 anode accelerated the enrichment of electro-active microbes.