The Influence Of Electrodes Modified With Nanomaterials Synthesized By Green Method On The Performance Of Microbial Fuel Cell(MFC)

Microbial fuel cell(MFC),which was one of the most promising eco-friendly electrochemical devices,has drawn remarkable attention since it could solve the crisis of energy shortage by converting the chemical energy in sewage directly into sustainable electrical energy.However,the low output efficiency and high cost limit the application of MFC in large scales.The electrode plays a vital role in improving the performance of MFC.To date,eucalyptus leaf extract is successfully used as a reducing agent to remove oxygen-containing functional groups due to its abundant active biomolecules.In this paper,to enhance the efficiency of power generation in MFC with cost effective method,green synthesis nanomaterials by eucalyptus leaf extract were used to modify to electrode.Firstly,graphene oxide(GO)was used to reduced graphene oxide(rGO)by eucalyptus leaf extract.FTIR and XRD results indicated that oxygen-containing functional groups were removed.Cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)were applied to test the electrochemical performance,which demonstrated PEI/rGO anode improved the performance with greater capacitance and smaller activation impedance(45 Ω).Moreover,PEI/rGO,PEI/GO were severally used as anodes in double-chamber MFC to investigate their impacting on the electricity generation,which showed that the internal resistance of PEI/rGO group was 243.87 Ω with the maximum power densities and output voltage of 18.77 W/m3 and 760 mV,respectively.These demonstrate that PEI/rGO film anodes can be applied as anode materials in MFC to improve the biocompatibility of anode,the electron transfer rate and the electricity generation.Iron-reduced graphene oxide nano-composite(Fe/rGO)were facilely fabricated through one-step method with eucalyptus leaf extract.The synthesized Fe/rGO was investigated by various characterization methods.The results disclosed that Fe NPs appeared as regular spherical particles were uniformly loaded onto rGO with significantly increasing dispersion.And the oxygen-containing functional groups on the surface were removed by the biomolecules from eucalyptus leaf extract.Furthermore,CV,EIS,LSV and RDE were applied to examine the catalytic activity and internal resistance of Fe/rGO,Fe NPs,rGO and Pt/C,which showed that Fe/rGO composite gained better ORR catalyst activity,lower activation internal resistance(8.4 Ω)and higher oxygen reduction(3.70)than its constituents.Fe/rGO was used as air-cathode of single-chamber MFC with a maximum output voltage of 580 mV and a maximum power density of 11.14 W/m3.Therefore,the green synthesis of Fe/rGO is a cheap and an efficient catalyst of cathode which can replace Pt/C.These findings not only support the development of an efficient method for the green synthesized of nanocomposite but also provide an effective approach to accelerate electricity production of MFC.