Microbial fuel cells(MFCs) are one of the promising green energy sources to produce electricity from organic wastes with the help of bacteria as catalyst. Although MFCs are not yet commercialized, they have drawn great attention as a environmentally friendly alternative energy source. However, there are still several challenges to overcome for MFCs to appear in industry. Currently, practical applications of MFCs are limited because of their low power output due to slow electron transfer between the bacterial cells and the electrode.
Among the various factors for improving the power output of MFCs, the performance of electrodes are considered to be one of the important aspects. A wide range of electrode materials and configurations have been tested and developed in recent years to improve MFC performance.
As well, the modification of anodic electrode surface with various nano-engineering techniques has been widely proposed to improve bacterial adhesion and electron transfer from bacteria to the electrode surface. Bacterial adhesion and the formation of a biofilm or network on the anode surface are essential for the efficient biological transfer of electrons in a MFCs. Various modification strategies including nanomaterials and fabrication methods have been developed so far to increase the electron-accepting ability of the electrodes and to improve electron transfer and power output.
This dissertation focuses on the modification of anodic electrode surface with nano-engineering techniques, and identifies the rational method of improving the power output of MFCs. The organization of this dissertation is as follows:

In Chapter 3 suggests a new anodic electrode surface modification. The anodic electrode surface was coated with Magnetite/MWCNT nanocomposite by directly applying a magnetic field and the E. coli-catalyzed ML-MFC was assembled. This conductive biocatalytic layers coated on the anode help the electron transfer between the bacteria and the electrode.

In Chapter 4, a novel Fe3O4/CNT nanocomposite were synthesized and employed for the modification of anodic electrode to enhance E. coli-catalyzed ML-MFCs performance. The Fe3O4/CNT nanocomposite modified anodes with various Fe3O4 contents were investigated to find the optimum ratio of the nanocomposite for the best MFC performance. In the Fe3O4/CNT nanocomposite modified anode, Fe3O4 nanoparticles help to attach Carbon Nanotube(CNT) on anode surface by its magnetic attraction and the anode surface is formed multilayer network. The CNT offers a better nanostructure environment for bacterial growth and helps electron transfer from E. coli to electrode resulting in the improving the power output of MFCs.

In Chapter 5, a novel Fe3O4/Carbon nanocomposite were synthesized and employed for the modification of anodic electrode to enhance E. coli-catalyzed ML-MFCs performance. The Fe3O4/Carbon nanocomposite modified anodes with various carbon nanomaterials were investigated to find the multilayer structure of the Fe3O4/Carbon nanocomposite for the best MFC performance.

In Chapter 6, the cytochrome overexpressing-engineered E. coli demonstrates superior electrocatalytic performance than the natural E. coli. The engineered E. coli-catalyzed MFC shows lower polarization and high power density in comparison to reported natural E. coli-catalyzed MFC. We demonstrate that overexpressing-engineered E. coli by recombinant can improve its direct electron transfer capability. This work provides an efficient and economic approach to biologically engineer bacteria for improvement of MFC performance.