Direct electron transfer in E. coli catalyzed MFC with a magnetite/MWCNT modified anode

Abstract

Although microbial fuel cells (MFCs) are not yet commercialized, they have drawn great attention as a low cost and environmentally friendly alternative energy source. There are still several challenges to overcome for MFCs to appear in industry. Currently, real-world applications of MFCs are limited because of their low power density due to slow electron transfer between the bacterial cells and the electrode. To solve this problem, a batch type MFC with modified anode surface has been investigated in this article. The carbon anode surface was coated with magnetite/MWCNT nanocomposite by directly applying a magnetic field and the Escherichia coli (E. coli) catalyzed MFC was assembled for polarization studies. This conductive biocatalytic layer coated on the anode helps the electron transfer between the bacteria and the anode, by forming micro channels of MWCNT between them. The magnetite in the anode creates a magnetic field and attracts the bacteria towards the anode layer, speeding up the electron transfer and enhancing the MFC performance even without any mediator. The mediator-less MFC with magnetite/MWCNT nanocomposite generates high power density of 1050 mW m−2, almost 30% more than our previous report created by E. coli K12 in mediated MFC. Conductivity and resistivity of the conductive biocatalytic electrode was also investigated with cyclic voltammograms and electrochemical impedance spectroscopy, respectively.