Preparation Of Bacteria-derived Biological Iron Oxide/Carbon Nanocomposite And Its Application In Microbial Fuel Cells

Microbial fuel cells(MFCs),as a unique bioelectrochemical device that uses electrochemically active bacteria to convert chemical energy into electrical energy,can generate electrical energy while microorganisms degrade organic matter in sewage into simple inorganic matter.Therefore,it has attracted more and more attention in renewable energy and wastewater treatment.However,problems such as the low power output of MFCs seriously affected its large-scale commercial application.In most MFCs,bacterial attachment and electron transfer related to energy conversion occur on the anode,the development and modification of electrode materials has become an effective way to improve the efficiency of MFCs.It has been proved that the modification of carbon electrode with composite materials of iron oxide and carbon with catalytic activity is a promising method to obtain large specific surface area electrode and improve the electron transfer between bacteria and electrode.However,the current iron oxide/carbon composite modified electrodes still has some problems in the application process,such as easy falling of the modified materials,low biocompatibility and so on,which affects the electron transfer rate between microorganism and anode.Here,this research has two new methods were developed to prepare iron oxide/carbon composite catalyst modified anode based on inorganic and organic carbon skeleton dispersed iron oxide.These modified anodes have the advantages of high catalytic activity,strong biological affinity and stable structure,which provides new ideas for its large-scale commercial application of MFCs in the future.Firstly,the Fe₂O₃/carbon nanotubes(CNTs)nanocomposite modified anode with high catalytic activity and conductivity was prepared based on the CNTs framework dispersed iron oxide.Secondly,based on the micro-dispersion of iron atoms by the organic carbon chain in the ferritin of Shewanella and the macro-dispersion of the bacteria on the electrode,an in situ carbonized bacteria method was developed to prepare biological iron oxide/carbon(Bio-FeO_x/C)nanomaterial modified anode with highly dispersed iron oxide.Finally,the mechanism of modified anodes to promot the performance of MFCs was clarified by characterizing the electricity generation performance,electrochemical performance and anode biofilm structure of MFCs with modified anodes.The Bio-FeO_x in the modifier was covalently dispersed in the nitrogen-doped carbon shell produced by the carbonization of the peptide chain,which gives the modified electrode high catalytic activity and reduces the charge transfer resistance of the electrode.The MFC with Bio-FeO_x/C nanomaterial modified anode showed the highest power density(0.530 W m^-2),which were 3.029 times and 2.585 times higher than that of the control MFC(0.175 W m^-2)and MFC-Fe₂O₃/CNTs(0.205 W m^-2),respectively.These results demonstrate that the Bio-FeO_x/C nanomaterial modified anode prepared based on the dispersion of the ferritin of the Shewanella outer membrane in the electrode has excellent bioaffinity and catalytic activity,which can significantly improve the power density of MFCs.In this paper,an in situ carbonization of bacterial method based on organic carbon framework to disperse iron oxide particles is developed to prepare iron oxide/carbon nanocomposite catalyst modified electrodes,which provides a new green strategy for the preparation of iron oxide/carbon nanocomposite catalyst modified electrodes.At the same time,it shows great application potential in the construction of high-performance MFCs,which has positive guiding significance for the development and application of high-efficiency MFCs.