Promotion of direct electron transfer between CN32 and carbon fiber electrodes via growth of α-FeO nanoarray.

The iron transport system plays a crucial role in the extracellular electron transfer process of . In this study, we fabricated a vertically oriented α-FeO nanoarray on carbon cloth to enhance interfacial electron transfer in CN32 microbial fuel cells. The incorporation of the α-FeO nanoarray not only resulted in a slight increase in flavin content but also significantly enhanced biofilm loading, leading to an eight-fold higher maximum power density compared to plain carbon cloth. Through expression level analyses of electron transfer-related genes in the outer membrane and core genes in the iron transport system, we propose that the α-FeO nanoarray can serve as an electron mediator, facilitating direct electron transfer between the bacteria and electrodes. This finding provides important insights into the potential application of iron-containing oxide electrodes in the design of microbial fuel cells and other bioelectrochemical systems, highlighting the role of α-FeO in promoting direct electron transfer.