Preparation Of Cu-based Oxygen Reduction Catalyst And Performance Of Microbial Fuel Cell

Microbial fuel cell（MFC）is a new type of energy storage and conversion technology,using the biocatalytic action of electricity-producing bacteria to degrade organic matter in sewage while generating electricity.However,the kinetics of cathodic oxygen reduction（ORR）of MFC is very slow,which hinders the large-scale application of MFC.Therefore,the development of non-noble metal catalysts with low cost,high activity and strong stability is the key in the field of MFC research.Metallized organic frames（MOFs）are widely used in electrocatalysis because of their high surface area,ordered porous structure and adjustable pore size.In this paper,Cu-NC-T,Cu/Co-NC-T and Cu/Co-NC@m S-T catalysts were prepared by high temperature pyrolysis using MOFs as precursor and template.The catalysts were characterized by XRD,XPS,BET,SEM and Raman,and electrochemical tests were conducted by CV,LSV,Tafel and EIS.In single-chamber MFC,the effects of pyrolysis temperature,heteroatomic doping and Si O₂protective calcination on the electricity generation performance of MFC were studied.The specific research contents are as follows:（1）A metal-organic framework of MOF-199 was prepared by a one-step hydrothermal method.A nitrogen-doped copper based polyporous carbon material Cu-NC-T was obtained by pyrolysis at different temperatures,which basically maintained octahedral morphology and had multistage pore structure.The initial potential and limiting current densities of Cu-NC-800 are 0.161 V and-6.256 m A·cm^-2,respectively,which are much higher than those of undoped Cu-C-800(0.123 V and-5.591 m A·cm^-2).When Cu-NC-800 is used as MFC cathode catalyst,its maximum power density and open-circuit voltage are 662.8±3.6m W·m^-2and 0.624±0.020 V,which are slightly lower than commercial Pt/C(815.0±6.2m W·m^-2,0.745±0.044 V).（2）Using 2-methylimidazole as organic ligand and nitrogen source,Cu/Co-ZIF was synthesized by one-step hydrothermal method.The dodecahedral Cu/Co-NC-T catalyst was prepared by pyrolysis at different temperatures.Cu/Co-NC-800 has higher initial potential and limiting current density(0.180 V,-7.247 m A·cm^-2vs.Ag/Ag Cl).When Co/Cu-NC-800 is used as MFC cathode catalyst,its maximum power density and open-circuit voltage are 774.2m W·m^-2and 0.713 V,slightly lower than commercial Pt/C(892.1 m W·m^-2,0.780 V).Bimetallic synergism can accelerate electron transfer,expose more catalytic active sites,and improve electrocatalytic activity.（3）Using hexadecyl trimethyl ammonium bromide as the pore guide template,the surface of dodecahedron was hydrolyzed by alkaline catalysis,coated with Si O₂shells.After high temperature pyrolysis,the Si O₂shells were removed by chemical etching,and N-doped bimetallic carbon materials（Cu/Co-NC@m S-T）were obtained.The Cu/Co-NC@m S-800catalyst has higher initial potential and limit current density(0.187 V,7.410 m A·cm^-2vs.Ag/Ag Cl).When Cu/Co-NC@m S-800 is applied to MFC,its open-circuit voltage and maximum power density are 0.797 V and 932±5 m W·m^-2,higher than Cu/Co-NC-800(0.713V,774±5 m W·m^-2)and slightly higher than commercial Pt/C(0.780 V,892±5 m W·m^-2),indicating that the protective calcination of m Si O₂can effectively inhibit the irreversible fusion and polymerization of Cu/Co nanoparticles during high temperature pyrolysis,so that the bimetallic particles and nitrogen are evenly distributed in the carbon nanoframe,thus improving the catalytic activity of ORR.