Iron-cobalt-nitrogen Co-doped Template Carbon Catalyst For Oxygen Reduction Reaction

Fuel cells(FC),as a device that directly converts chemical energy into electrical energy,has the advantages of high efficiency and environmental friendliness,and has attracted the attention of researchers.At present,fuel cell cathode oxygen reduction(ORR)catalysts are mainly precious metal platinum with high price and small reserves,so it is of great significance to replace them with non-precious metal based ORR catalysts.Metal nitrogen modified carbon catalysts are considered to be the most promising alternative materials because of their high ORR activity and cost effectiveness.In this paper,mesoporous silica SBA-15 is used as template,mesoporous silica SBA-15 with metal salt solution(FeCl3 and K3[Fe(CN)6]mixture)impregnated SBA-15,iron base nitrogen doped carbon prepared by acetonitrile CVD method(Fe-N-C),the cobalt phthalocyanine was further compounded with the prepared template carbon by solvothermal method,the bimetallic nitrogen doped porous carbon(Fe-Co-N-C)catalyst with good ORR catalytic activity was prepared.Scanning electron microscopy(SEM),X-ray diffraction(XRD),physical adsorption(BET),X-ray photoelectron diffraction and other characterization methods were used to analyze the morphology and structure and the composition of surface elements of the composite and the composition of surface elements.At the same time,electrochemical analysis techniques such as cyclic voltammetry(CV)and linear voltammetry scanning(LSV)were used to explore the electrochemical properties of catalysts,the details are as follows:(1)SBA-15 was impregnated with mixed solution of metal salt solution FeCl3 and K3[Fe(CN)6],template carbon was prepared by acetonitrile CVD method,and the polymer polyphthalocyanine was compounded with template carbon by solvent-heat method.The bimetallic nitrogen-doped porous carbon catalyst(Fe-Co-N-C)was prepared.SEM results show that Fe-Co-N-C can replicate the ordered mesoporous structure of the original template SBA-15 XPS analysis showed that the nitrogen-containing functional groups were mainly pyridine nitrogen,pyrrole nitrogen and graphite nitrogen.BET test results showed that the specific surface area and pore volume of Fe-Co-N-C-4h-900 sample were 307.70 m2·g-1 and 1.12 cm3·g-1,respectively.The composite porous structure was found in the material,in which ordered mesoporous channels were favorable for material and electron transmission.(2)The Fe-Co-N-C-4h-900 catalyst had the highest ORR activity in alkaline medium.The Fe-Co-N-C-4h-900 catalyst had the highest ORR activity in alkaline medium.lt is shown in the limit current density(JL=-4.6 mA·cm-2),the initial potential(Eonset=+0.19 V)and the half-wave potential(E1/2=-0.14 V),and the electron transfer number n=3.97 at-0.5 V,reflecting that the electron transfer number of Fe-Co-N-C-4h-900 is close to 4 and follows the four-electron transfer path;The i-t and ADT test results showed that the Fe-Co-N-C-4h-900 electrocatalyst had good stability,which was mainly due to the bimetal and a large number of catalytic active sites of pyridine nitrogen in the material,as well as the synergistic effect with the composite porous structure and ordered mesoporous in the material.