Research on Anode Materials for High-Performance Microbial Fuel Cell Based on Micro/nano Materials
Author:Zeng Li Zhen
Environment pollution and energy shortages are the two crisis that we faced today.Microbial fuel cell(MFC)as one type of "green" energy source has received great interest among researchers due to its potential application for simultaneous waste treatment and electricity generation.However,the low power density and poor long-term stability limit its practical applications.The reason is mainly due to the small amount of microorganisms attached to the surface of the anode and the slow transfer of electrons between the microorganisms and the electrodes that limit the current generation and power output of the MFC.The anode,as a carrier for the attachment of electrogenic microorganisms,not only affects the biofilm formation but also affects the transfer of electrons from the microorganisms to the anode,which has a crucial impact on improving the performance of MFC.Finding and developing anode materials with high performance and good biocompatibility and low cost,and using them in MFC anodes to improve the power generation capability of MFC will further promote the application of MFC.To improve the performance of MFC,carbon/cotton based materials with different surface morphologies were designed and prepared.The effect of the surface morphology,physical and chemical properties,and electrochemical property on the performance of MFC was investigated.Main content in this study are as follows:(1)The anode material is a crucial factor that significantly affects the cost and performance of MFC.In this study,a novel macroscale porous,biocompatible,highly conductive and low cost electrode,carbonized polydopamine-modified cotton textile(NC@CCT),is fabricated by using normal cheap waste cotton textiles as raw material via a simple in situ polymerization and carbonization treatment as anode of MFC.The physical and chemical characterizations show that the macroscale porous and biocompatible NC@CCT electrode is coated by nitrogen-doped carbon nanoparticles and offers a large specific surface area(888.67 m2 g-1)for bacterial cells growth,accordingly greatly increases the loading amount of bacterial cells and facilitates extracellular electron transfer(EET).As a result,the MFC equipped with the NC@CCT anode achieves a maximum power density of 931 ± 61 mW m-2,which is 80.5%higher than that of commercial carbon felt(516 ± 27 mW m-2)anode.Moreover,making full use of the normal cheap waste cotton textiles can greatly reduce the cost of MFC and the environmental pollution problem.(2)A novel macroscale porous structure electrode,molybdenum carbide nanoparticles-modified carbonized cotton textile(Mo2C/CCT),was synthesized by a facile two-step method and used as anode material for high-performance microbial fuel cell(MFC).The characterization results show that the carbonized cotton textile modified with Mo2C nanoparticles offers a great specific surface area(832.17 m2 g-1)for bacterial adhesion.The MFC using Mo2C/CCT anode delivers the maximum power density of 1.12 W m-2,is 51%and 116%higher than that of CCT and unmodified carbon felt anodes under the same conditions.The high power density is mainly owing to Mo2C nanoparticles with good biocompatibility and high conductivity and superior electrochemical activity,as well as the macroscale porous structure of carbonized cotton textile,which facilitate the formation of electroactive biofilm and improve the electron transfer.This paper introduces a feasible way to synthesis cost-effective and high-performance anode material for MFC.(3)A novel bi-component composite of porous self-assembled micro-/nanostructured Ni0.1Mn0.9O1.45 microellipsoids as high-performance anode material for MFC is successfully synthesized via a simple coprecipitation reaction in microemulsion and calcination method in air atmosphere.The morphology and structural characterization indicate that the as-fabricated Ni0.1Mn0.9O1.45 product is consist ofMn2O3 and NiMn2O4(n(Mn2O3):n(NiMn2O4)=0.35:0.1)and has a porous microellipsoidal morphology.The microellipsoids are compose of numerous layered micro-/nanostructured blocks and the special porous microellipsoids structure of Ni0.1Mn0.9O1.45 offers a large specific surface area for bacteria adhesion.The porous Ni0.1Mn0.9O1.45 microellipsoids as anode electrocatalyst for MFC exhibits excellent electrocatalytic activity to promote the EET between the anode and bacteria,hence improves the performance of MFC.The MFC equipped with Ni0.1Mn0.9O1.45/CF anode achieves a maximum power density of 1.39 ± 0.02 W m-2,is significantly higher than that of commercial carbon felt anode.This work proposes a new method for the synthesis of high-performance and environmentally friendly anode material for MFC.(4)Preparing multilayer materials without using any templates is a great challenge.In this work,γ-MnO2/GO(graphene oxide)composite with novel multilayer nanoflakes structure as high-performance anode material of MFC,is fabricated via a facile chemical precipitation method without template.The physical and chemical characterizations show that multilayerγ-MnO2/GO nanoflakes possess high conductivity and offer a large surface area for bacteria adhesion,consequently increase the loading amount of bacteria and facilitate the EET between the anode and bacteria.On the one hand,the three-dimensional structure increases its specific surface area,which favors the attachment of bacterial cells and increases the biomass.On the other hand,γ-MnO2 has pseudocapacitive properties,the redox reaction of Mn3+ and Mn4+promotes the EET efficiency,improves the anode performance,and thus enhances the power density of MFC.By combining the advantages of γ-MnO2 and GO,γ-MnO2/GO composites exhibit excellent electrochemical performances,the MFC equipped with γ-MnO2/GO modified on carbon felt anode delivers a maximum power density of 1.13±0.09 W m-2,is 119%higher than that of bare carbon felt anode under the same condition.The results demonstrate that the multilayer γ-MnO2/GO nanoflakes is a promising anode material for high-performance MFC applications.