Preparation And Electrochemical Properties Of Co_xFe_3-xO₄ Nanomaterials

With the development and progress of the society,people have put forward higher request for the volume of a portable energy,energy density,cost and other factors.Among them,rechargeable metal air batteries received great attention thanks to high energy density,low cost,environment friendly,and other prominent feature.However,the slow kinetic reaction speed of the air electrode limits the energy input and output of the whole battery,so the catalyst must be used to improve the reaction speed of the air electrode.In the article,we prepared the normal spinel Fe Co₂O₄ nanoparticles and inverse spinel CoFe₂O₄ nanoparticles by hydrothermal method through low-cost control of atomic ratio.By means of XRD Rietveld finishing and XPS analysis,their crystal structure contents were determined,and the influence of crystal structure on oxygen reduction reaction and oxygen evolution reaction was studied.After we identified the spinel nanometer materials with better electrochemical performance,in order to reduce the aggregation of nanomaterials,we further prepared two morphologies of inverse spinel CoFe₂O₄ nanoparticles materials with hollow spheres and hollow cubes,SEM and EDS were used to study their micromorphology,and the results showed that the two morphologies could improve the gas transport rate greatly,thus improving the electrochemical performance.Graphene was a kind of two-dimensional nanomaterials with high conductivity,high specific surface area,easy adsorption of O₂,We used graphene load CoFe₂O₄ nanoparticles and CoFe₂O₄ hollow spheres to study the effect of graphene on the oxygen reduction reaction of CoFe₂O₄ nanomaterials,finally we got excellent electrochemical performance of graphene load CoFe₂O₄ hollow spheres,the rate of oxygen reduction reaction was similar to that of the precious metal catalyst Pt/C,the performance attenuation was much lower than that of Pt/C catalyst.