Study On Anode Materials To Improve The Performance Of Microbial Fuel Cells

Microbial fuel cell (MFC) is an innovative power output device, which utilizes microorganisms as catalysts to metabolize fuel and convert chemical energy into electrical energy. It possesses both waste disposal and electricity output at the same time, and is a promising new energy.Electron transfer on anode surface is the key step during the whole electricity-generating process of MFC. The intrinsic properties of anode materials directly affect bacteria adhesion and electron transfer. Therefore, it is quite important to choose anode materials in order to improve MFC performance. The essential requirements for anode materials include high conductivity, high specific surface area, high porosity, non-corrosiveness, non-bacteria clogging, good compatibility and low cost.In this dissertation, we utilize ionic liquid as solvent and supporting electrolyte to polymerize EDOT monomer and prepared graphene/PEDOT and Fe3O4/PEDOT hybrid, respectively. The structures, morphologies and properties were characterized by using some techniques such as fourier transform infrared (FTIR), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), cyclic voltammogram (CV) and so on. Base on the above properties, we studied the performance of these two hybrids as anode for MFC, respectively. The main results are summarized as follows:1. Graphene/PEDOT Hybrid as Anode for High-performance Microbial Fuel Cell A graphene/poly(3,4-ethylenedioxythiophene)(G/PEDOT) hybrid anode for Escherichia coli MFC was fabricated through galvanostatic electropolymerization. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests illustrated that the G/PEDOT hybrid anode possessed large active surface area and low charge-transfer resistance. Scanning electron microscopy (SEM) was used to investigate the bacteria growth on G/PEDOT anode and a compact biofilm was formed on the hybrid anode due to the electrostatic interaction between the negatively charged bacteria and positively charged PEDOT backbone. The G/PEDOT anode generated a maximum power density of873mW/m2, which is about15times higher than that of CP (55mW/m2) in an H-shaped dual-chamber MFC. All the experimental results suggested that the G/PEDOT hybrid is a promising MFC anode material.2. Fe3O4/PEDOT Hybrid as Anode for Shewanella oneidensis Microbial Fuel CellsWe first synthesize carboxyl group functionalized Fe3O4nanoparticles, and fabricate Fe3O4/PEDOT hybrid via dip-dry method. Then, EIS and SEM are used to characterize the hybrid and the test results reveal the Fe3O4/PEDOT hybrid possesses low charge transfer resistance and high bacteria loading. Finally, Fe3O4/PEDOT hybrid is fixed in MFC as anode to test its performance. The Fe3O4/PEDOT anode generated a maximum power density of935mW/m2, which is about10times higher than that of CP (92mW/m2) in MFC. All the experimental results suggested that the hybrid is a promising MFC anode material.