Microbial Fuel Cell For Electricity Generation Based On Foam Metal Electrode

In the 21st century, great attentions have been focused on the novel technology of energy exploration and utilization because of the international tension of energy crisis and environmental contamination. Microbial fuel cells (MFC) are devices that can be used for direct bioelectricity generation. The unique way for energy production from MFC provides a creative method to resolve the energy crisis and water environments. Currently, the development of microbial fuel cells are still faced with many challenges, the complex cathode structure and poor power densities produced are one of the problems. Thus, the paper from the cathode preparation, structure , anode modification and electricity generation studies on the questions.In this study, a novel laminated nickel foam (NF) without coating diffusion layer is using as air-cathode. Multiple NFs are applied in order to optimize the performance of the cathode. The surface morphology, hydrophobicity, oxygen diffusion of the laminated NF are investigated by SEM, contact angle measuring instrument and oxygen analyzer. The preparation of NF cathode under a pressure of 40 Mpa presents the surface with obvious holes and convex-concave. It appears that when one layer NF layer applied on the diffusion layer first present a contact angle of 69°. Then, a good hydrophobic performance is observed with two layers involved in the diffusion layer preparation, and five NFs layers achieves the highest contact angle of 166.8°, reflecting the more the nickel foam layer applied, the higher the contact angle. The oxygen diffusion coefficient decrease with the increasing number of the NF layer, and oxygen diffusion coefficient is in a linear relationship with the number of the NF layer. Under two or three NF layers, the MFC is the best performance, achieve an open up voltage to 0.64 V and the highest maximum power density of 720 mW/m2. EIS (electrochemical impedance spectrum) test shows that the electrode resistance is about 8Ω. For a long time operation, the results proves it a stable and workable structure.Under a constant potential 0.55 V, nickel foam anodes are modified with polypyrrole/ anthraquinone-2-sulfonic acid sodium (PPy/AQS). SEM indicated that after modified, electrode surface forms a layer of dense coating with some small spherical particles. The cyclic voltammetry test found in the electrode modified with 10 C PPy/AQS are the best performance with the highest capacitance, maximum output power up to 2000 mW/m2, and electrode resistance is about 10Ω. Compared with the carbon felt modified PPy/AQS, the maximum output power of nickel foam anodes is 1.8 times that of the modified carbon felt, and the maximum output voltage increases nearly 0.1 V. The results show this modification can significantly enhance the electrical properties of MFC.