Investigation About Electrical Properties Of Dual-chamber Microbial Fuel Cell With Different Carbon-based Anode Material

Microbial fuel cells （MFCs） are promising devices featured for using microorganisms as catalysts to oxidize organic or inorganic matters and directly convert chemical energy into electrical energy. One of the most promising applications for MFCs is to use them as a method of simultaneously treating wastewater while accomplishing power generation. How to increase the power density has become the largest technical challenge. The anode material plays a crucial role in power output. Carbon-based anode materials have been widely used in MFCs. However, the conductivity and biocompatibility of carbon-based materials still have space to improve.In the work reported here, we modified carbon cloth（CC） anodes by concentrated nitric acid soaking（CC-A）, high temperature heating（CC-H）, nitric acid electrolyte oxidation（CC-X）, ammonia electrolyte oxidation（CC-N）, which have the advantage of mechanical integrity and ease of handling. Moreover, we modified graphite felt（SMZ） anodes by carbon nanotubes（SMZ-CNTs） and polyaniline（SMZ-PANI）. We mainly studied power output and electrochemical property of these different anode materials in dual-chamber microbial fuel cells. Ultimately we determined the reasons for showing different results in power output. The surface morphologies and surface elements were investigated by the scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS） techniques, Internal resistance R_int was measured by Electrochemical Impedance Spectroscopy （EIS）, the specific surface area of each anode was measured based on Multipoint Brunauer-Emmett-Teller （BET） adsorption isotherm.The experiment results showed that the stable maximum voltage was0.42-0.46V, the maximum power density was333mW/m2, R_int was251Ω for CC; the stable maximum voltage was0.52-0.58V, the maximum power density was480mW/m2, R_int was202Ω for CC-A; the stable maximum voltage was0.80V, the maximum power density was687mW/m², R_int was162Ω for CC-H; the stable maximum voltage was0.48-0.49V, the maximum power density was396mW/m², R_iunt,t was212Ω for CC-X; the stable maximum voltage was0.47V, the maximum power density was372.1mW/m², R_int was106Q for CC-N; For SMZ anode material, the stable maximum voltage was about0.39V. the maximum power density was38mW/m². R_int was275Ω:For SMZ-CNTs anode material, carbon nanotubes can enhance electron transfer process from bacteria to electrodes, so the stable maximum voltage reached0.47-0.48V. the maximum power density was654mW/m2. R_int was235Ω; For SMZ-PANI anode material, the stable maximum voltage was about0.48-0.52V, the maximum power density was64mW/m2, Rint was191Ω. Scanning electron microscopy （SEM） results indicated that the increase of power generation was attributed to the increase of bacteria counts attached to anodes. The power output of the MFC increased along with the increase of the N1s/C1s ratio, which was proved by X-ray photoelectron spectroscopy （XPS） analysis.As a result, an effective method for improving power generation in microbial fuel cell was demonstrated. In future the research about modifying anode material should be focused on increasing the surface N1s/C1s ratio.