Study On Production Performance Of Microbial Fuel Cells Based On Graphene Modified Cathode

Microbial fuel cell is a new kind of green energy equipment,which uses microorganisms to decompose waste water and produce electricity at the same time.Therefore,it has a foresight in the treatment of waste water,together with the production of electricity.At present,low power output and high cost are perceived as the two major bottlenecks in the commercialization of MFC.The cathode materials is the key factor determining the electricity generation and cost of MFC.Graphene,as the new two-dimensional nanomaterial,which has higher specific surface area,conductivity,carrier transport rate and biocompatibility than other carbon materials.Therefore,the modification of graphene for the cathode of MFC has great potential.Based on this,the feasibility of modified graphene for MFC cathode modification was explored,which laid a foundation for graphene modified cathode MFC.In this work,graphite oxide was synthesized by modified Hummers method and N-doped graphene based cobalt oxide?N/CoO_x-G?was synthesized by one-step hydrothermal method.The crystal structure of metal oxides,functional groups,reduction effect of graphene and types of doped N atoms were characterized by XRD?X-ray diffusion spectroscopy?,Fourier transform infrared spectorscopy?FTIR?and Raman spectroscopy,respectively.The results showed that the reduction effect of graphene was good.CoO_x has been distributed on graphene surface and N atom was doped with pyrrole,pyridine and graphene.The oxygen reduction electrocatalytic activity and electrocatalytic performance of N/CoO_x-G as cathode for MFC were evaluated that had superior oxygen reduction activity.The maximum voltage of MFC can reach 626 mV,which was higher than that of CoO_x-G 506 mV,N-G 484 m V,carbon felt?C?236 m V,and what is more the maximum power density and internal resistance were 801 mW/m²and 160.4?,was 20.6 times higher than that of carbon felt cathode?C?with the internal resistance reduced by 818.1?.The cell has good stability with 3.7 voltage drop after four months of operation.In this work,N-doped graphene based manganese dioxide N/MnO₂-G was prepared by one-step hydrothermal method.The results of XRD,FTIR,XPS and Raman spectra showed that the reduction effect of graphene was good.MnO₂ was successfully immobilized on the surface of graphene with the pyrrole,pyridine and graphite N atom.The oxygen reduction electrocatalytic activity and electrocatalytic performance of N/MnO₂-G as cathode catalyst for MFC were evaluated that N/MnO₂-G had good oxygen reduction activity.The maximum voltage and the maximum power density were 576 mV and 435.8 m W/m²which was lower than 626 mV and 801 m W/m²of N/CoO_x-G.The the voltage of the cell was reduced by 8%after four months of operation.Furthermore,a simple method of directly adding graphite oxide dispersion into MFC cathode chamber to improve the cathodic oxygen reduction performance was explored.The results showed that GO can be reduced into graphene?m-RGO?by microorganism on the cathode which can improve the electrical properties of MFC.The maximum voltage can reach437 m V,which was higher than that of C?236m V?.The maximum power density of 325.1mW/m²was 8.8 times that of C,which can effectively reduced the internal resistance of cathode.The voltage of the cell was reduced by 15%after 4 months of operation,which was a green and sustainable technology.By modifying the cathode of MFC with chemical and biological means,which finally achieved the purpose of reducing the internal resistance and improving the electricity generation performance of MFC.To some extent,the cost of cell construction was reduced.The experimental results will provide the theoretical basis for the practical application of MFC in the future.