Preparation Of Amino Functionalized Metal Organic Framework Compound And Its Application In Air Cathode Microbial Fuel Cell

Microbial fuel cells?MFCs?are devices that convert the chemical energy of wastewater organic matter into electrical energy.They have the dual function of generating electrical energy at the same time as sewage treatment,and have been widely concerned in the fields of energy development and environmental protection..Among many types of MFC,the air cathode MFC is a hot research object in the field because of its direct use of oxygen as an electron acceptor.It is also one of the most promising configurations for large-scale commercial applications.However,the oxygen reduction reaction?ORR?of air cathode MFC often requires the assistance of an oxygen reduction catalyst to proceed smoothly.The most commonly used catalysts are Pt-based catalysts.However,Pt has scarce reserves in nature and is expensive.As a result,when Pt-based materials are used as catalysts,the cost of air cathode MFC is greatly increased,making air cathode MFC impossible to achieve large-scale commercial applications.Still can only stay at a small-scale laboratory level.In order to find alternatives to Pt-based materials,a large number of low-cost cathode catalysts have been developed and used in air cathode MFC.However,the reduction in the cost of these catalysts is often accompanied by a reduction in the electrical performance of the air cathode MFC.Therefore,the development of low-cost cathode catalyst materials with high catalytic activity has become a hot research topic in air cathode MFC.This article focuses on the topic of preparing"low-cost and high-efficiency"air cathode catalysts.Based on metal-organic framework compounds?MOF?with excellent electrochemical catalytic properties,copper-based metal organic framework materials?Cu-MOF?Copper-based metal organic framework material?Cu-MOF-NH₂?functionalized with amino groups.A series of characterization methods such as Fourier infrared spectroscopy,X-ray diffraction,and scanning electron microscope were used to characterize the physical and chemical properties of the material,and the influence of the introduction of amino groups on the physical and chemical properties of Cu-MOF was analyzed.At the same time,an air cathode electrode using Cu-MOF as a catalyst and an air cathode electrode using Cu-MOF-NH₂as a catalyst were prepared by the"one-pot method",and the two air cathodes were electrochemically subjected to cyclic voltammetry Activity test,and use the basic air cathode without catalyst as a comparison.Then the two air cathode electrodes were applied to the air cathode MFC.The changes of the electricity generation performance of the two catalysts for the air cathode MFC were observed and studied.The basic air cathode without catalyst was also used as a comparison.Finally,by analyzing the composition of the anode surface flora,the influence of the application of the two catalysts in the air cathode MFC on the composition of the anode surface flora was discussed.Characterization of the physicochemical properties of the two materials found that the introduction of the amino group changed the electron distribution on the benzene ring.The electrons tended to the metal center,which caused the electrons to be concentrated near the metal center and caused polarization.Therefore,the insertion of the amino group made benzene The ring and Cu-MOF-NH₂structure are positively charged.This change leads to a more regular internal crystal structure of Cu-MOF-NH₂material,while improving the pore structure of Cu-MOF-NH₂itself,showing a larger specific surface area.The good hydrophilic properties of the amino group also bring excellent hydrophilic properties to Cu-MOF-NH₂.At the same time,it was found by scanning electron microscope observation that Cu-MOF-NH₂was more uniform and firm on the carbon cloth substrate than Cu-MOF.This is because the amino group of Cu-MOF-NH₂interacts with the carboxyl group on the surface of the acidified carbon cloth,and the overall positively charged Cu-MOF-NH₂is repulsive,which leads to the ability of Cu-MOF-NH₂in carbon The distribution on the cloth substrate is more uniform and reliable.Through electrochemical activity tests,it was found that the cyclic voltammetry curves of the Cu-MOF-NH₂modified electrode and the Cu-MOF modified electrode have obvious redox peaks,while the Cu-MOF-NH2 modified electrode has a larger Chemically active area.Through the MFC power generation performance test,it is found that the Cu-MOF-NH₂modified air cathode brings considerable power density output to the air cathode MFC,and the maximum power density reaches 0.64 W·m^-2,which is the Cu-MOF modified air cathode 1.4 times(0.45 W·m^-2),3.2 times(0.20W·m^-2)of the base air cathode without catalyst.At the same time,through the analysis of the composition of the bacteria attached to the anode surface,it was found that the use of catalyst materials can promote the growth and reproduction of the electricity-producing bacteria on the anode surface,which on the other hand promotes the electricity generation output of the air cathode MFC.When using Cu-MOF-NH₂as the air cathode catalyst to run the air cathode MFC,the proportion of the electricity-producing bacteria on the anode surface even exceeded 60%,which was higher than that when using Cu-MOF as the air cathode catalyst to run the air cathode MFC.Proportion of electricity-producing bacteria on the anode surface.This shows from the side that Cu-MOF-NH₂modified air cathode can bring higher power output to air cathode MFC.This work explores a method for optimizing the use of ordinary MOF materials as air cathode catalysts.The introduction of simple functional groups changes the physical and chemical properties of MOF materials to make them have better electrochemical catalytic activity.The large-scale promotion and application of MFC has certain guiding significance.