Application Study Of Polyaniline-Graphene Modified Electrode In Microbial Fuel Cell

Microbial fuel cell?MFCs?is a promising technology that can achieve sustainable energy production.It can convert the chemical energy stored in organic fuel as a nutrient substrate into electrical energy through the metabolism of exoelectrogen.At the same time,it can degrade organic pollutants in wastewater.In the course of its operation,the biofilm produced by the exoelectrogens on the surface of the electrode acted as catalyst.Therefore,the electron transfer between the bacteria and the electrode has a crucial impact on the overall performance of the microbial fuel cell,which is the key to its practical application.The electrode modification technology can effectively improve the electrochemical performance of the electrode,improve the electron transfer,simplify the preparation process,reduce the preparation time,and improve the preparation efficiency.And it is worth exploring in depth.In this paper,the in-situ polyaniline modified layer is formed on the surface of the three-dimensional carbon felt electrode using a simple and effective constant current polymerization method.The three-dimensional carbon felt electrode with in-situ modified graphene layer is obtained by electrochemical partial exfoliation method.The combination of modification methods in order to modify the electrode and improve the electron transfer ability of the electrode.In the study,the material characteristics of the new electrode and the enhancement mechanism of the MFCs electricity generation performance were elaborated.The specific research results mainly include:1.A simple constant current polymerization method was used to initiate the in-situ polymerization of aniline on the surface of the carbon felt electrode with a 10 mA current within 10 minutes to prepare a PANI modified electrode.Further research found that the maximum output voltage of the MFCs of the new electrode reached?309±24?mV,which was 3 times that of the blank carbon felt electrode in the control group.Meanwhile,the maximum output power density was?450±36?mW·m^-2,which was6 times higher than the control.The new electrode can improve the performance of MFCs by increasing the specific surface area and improving the direct electron transfer between the bacteria and the electrode.2.Using the electrochemical exfoliation method,a partially exfoliated in-situ graphene modified three-dimensional electrode?ExGR electrode?was prepared.The carbon felt electrode was cyclic voltammetrically scanned within the voltage range?-0.5².5 V?,and the ExGR electrode was formed within 5 minutes.Further research found that the maximum output voltage of the MFC of the new ExGR electrode reached?180±6?mV,which was twice that of the control.Meanwhile,the maximum output power density was?137±9?mW·m^-2,which was increased by 1.79 times of the control.The new ExGR electrode can improve the performance of MFCs by increasing the specific surface area and improving the direct electron transfer between the bacteria and the electrode.3.Combined with the above method of constant current polymerization of polyaniline and electrochemical exfoliation of graphene,composite modified ExGR/PANI electrode and PANI/ExGR electrode were prepared and applied to MFC.The maximum output voltage of the ExGR/PANI electrode is?270±18?mV,and the maximum output voltage of the PANI/ExGR electrode is?253±17?mV,which is2.86 and 2.69 times of the control,respectively.The maximum power density of ExGR/PANI is?357±5?mW·m^-2,and the maximum power density of PANI/ExGR is?340±21?mW·m^-2,which is 4.66 and 4.44 times of the control,respectively.The results proves that two sets of composite modified electrodes can significantly improve the electrochemical performance of the electrode,thereby improving the power generation capacity of MFCs.However,the performance of MFCs is worse than that of PANI electrode modified with polyaniline alone,which shows that electrochemical exfoliation and constant current polymerization cannot form a synergistically improved composite material.And different modification orders cannot further improve the performance after compositon,too.The preparation scheme proposed in the paper will provide technical guidance and theoretical basis for electrode modification technology and the practical application of microbial fuel cells.