Application Of Novel Graphite Paper And Graphene In Microbial Fuel Cell

Microbial fuel cells （MFCs） are renewable energy devices that can convert organicsubstrates into electricity via the catalyzation of microorganisms. The low power density ofMFCs remains one of the main obstacles for their practical applications. Aside from all theother factors affecting the MFCs performance, which include cell design, inoculum, substrate,proton exchange material and electrode surface areas, etc. the fabrication materials of anodeand cathode play a profound role in influencing the power generation. The anode material candetermine the actual accessible area for bacteria to anchor and affect the interfacial electrontransfer resistance. Therefore, a high-performance anode material is most essential to improvethe power outputs of MFCs. In cathode, oxygen is an ideal electron acceptor due to itsaccessibility in environment and clean product. However, the poor kinetics of oxygenreduction reaction in the MFCs cathodic medium limits the efficient utilization of oxygen asfinal electron acceptor for most cathode materials.In this study, novel graphite paper （GTS） and graphene were used to improve theperformance of MFCs. Some innovative findings have been found as follows:（1） GTS has been used as anodic catalyst in MFC based on E.coli （ATCC25922） andcharacterized by discharge experiment and polarization curve. Findings from thesemeasurements revealed that GTS showed an excellent electrochemical performance. Thetwo-chambered MFC operated with the GTS anode delivered a maximum power density of2249mW m^-2. Scanning electron microscopy （SEM） results indicate that the high poweroutput could be attributed to the high biocompatibility of the GTS.（2） A graphene-modified stainless steel mesh （GMS） has been used as anodic catalyst ofMFCs based on E.coli. The electrochemical activities of stainless steel mesh （SSM）,polytetrafluoroethylene （PTFE） modified SSM （PMS） and GMS have been investigated bycyclic voltammogram （CV）, discharge experiment and polarization curve measurement. TheGMS shows better electrochemical performance than those of SSM and PMS. The MFCequipped with GMS anode delivers a maximum power density of2668mW m^-2, which is18times larger than that obtained from the MFC with the SSM anode and is17times larger thanthat obtained from the MFC with the PMS anode.（3） The morphologies and surface elemental analysis of graphene were characterized bytransmission electron microscopy （TEM） and X-ray photoelectron spectroscopy （XPS）. Theelectrochemical activity was evaluated by CV. Graphene exhibited high oxygen reductionactivity. The MFC operated with the graphene cathode delivered a maximum power density of 289mW m^-2, which demonstrated that the graphene is promising candidate for application ofMFC.（4） Noncovalent functionalization of graphene with iron tetrasulfophthalocyanine（FeTsPc） is achieved not only to prevent the aggregation of graphene but also form anefficient electrocatalyst for the oxygen reduction reaction （ORR） in a dual-chamber microbialfuel cell. The electrochemical activity of the FeTsPc-functionalized graphene（FeTsPc-graphene） is evaluated towards the ORR using CV and linear sweep voltammogram（LSV） methods. More positive peak potential and larger peak current of oxygen reduction arefound using FeTsPc-graphene electrode as compared to FeTsPc electrode. The maximumpower density of817mW m^-2obtained from the MFC with a FeTsPc-graphene cathode ishigher than that of523mW m^-2with a FeTsPc cathode and is close to that of856mW m^-2with a Pt/C cathode. Thus, FeTsPc-graphene nanocomposites can be a good alternative to Ptcatalyst in MFCs.