Development of new nanostructured electrodes in Microbial Fuel Cells (MFCs)

Abstract

The aim of my thesis work is to investigate new nanostructured materials, obtained by the electrospinning technique, in order to design 3D arrangement of the electrodes, leading thus to improve the energy efficiency of energy production devices, such as microbial fuel cells (MFCs). The carbon nanofibers reveal to be the most promising material in the field of bio electrochemistry; in fact, up to now the best performing microbial fuel cells are fabricated using carbon and carbon based material electrodes. To further enhance the performances of bio anodes and bio cathodes, a set of properties are then required to be overcome, such as a proper surface morphology and chemistry, good biofilm adhesion and electron transfer, and a good electrical conductivity. This work aims to demonstrate that the electrospun nanofibers own all the necessary properties, revealing themselves as the most innovative and promising structures for anodes and cathodes for microbial fuel cells. The nanofibers ensure all the properties listed above; in particular, during my Ph.D. I have investigated and studied the carbon based nanofibers to be applied as cathode and as anode in these kind of the devices. In this thesis, it will be demonstrated that the nanostructured electrodes improve the efficiency devices thanks both to the low impedance and to the interaction with the microorganisms. The high micrometric porosity characteristics of the realized anodic material create the ideal habitat for the microorganism's proliferation. Moreover, different solution for the cathode material have been developed using ceramic nanofibers, such as MnxOy nanofibers and carbon nanofibers, in order to improve the performance of the devices. The layer made of these nanofibers, in fact, catalyzes the oxygen reduction reaction if the oxygen is used as terminal electron acceptor in the devices; thus these catalysts can substitute the platinum layer, which is the most used today, granting a cheaper and eco friendlier material.