Nano-Fe3O4 coated on carbon monolith for anode enhancement in microbial fuel cells

Anode materials were vital for power production in microbial fuel cells (MFCs). By freeze-drying and carbonization, porous carbon monolith derived from wax gourd (WGCM) was prepared. WGCM was then coated by nano-Fe3O4 to obtain the nano-Fe3O4/WGCM anode. WGCM anode increased the maximum power density of the MFCs from 430.6 mW/m2 to 906.6 mW/m2, while nano-Fe3O4/WGCM anode further promoted it to 1438.8 mW/m2. WGCM had a three-dimensional (3D) microporous network structure, a hydrophilic surface and good conductivity, which enhanced biofilm formation and reduced internal resistance. Fe3O4 increased Geobacter enrichment on anode surface, a popular electricigen in MFCs. Calculated from anode surface microbial cell density and the relative abundance, Geobacter on the nano-Fe3O4/WGCM increased by 41.4% compared with the WGCM anode. The results demonstrated that the preparation of carbon monolith coated with nano-Fe3O4 was a promising method for anode enhancement in MFCs.