Preparation And Electrocatalytic Properties Of Transition Metal And Nitrogen Co-Doped Porous Carbon Materials

Zinc-air battery is favored by researchers because of its advantages of environmental protection,no pollution,high energy density and rich resources.However,in practical applications,the development of zinc-air batteries is contained by two major problems.On the one hand,the oxygen reduction reaction（ORR）on the cathode during discharge and the oxygen evolution reaction（OER）on the anode during charging both have slow reaction kinetics.On the other hand,the ORR and OER reaction barriers are high.To solve these two problems,expensive and less stable noble metal-based catalysts are currently used commercially.In order to find alternative materials for noble metal-based catalysts,the component optimization and morphology regulation of carbon materials were studied in order to achieve the purpose of"accelerating the reaction dynamics","reducing the reaction barrier"and"reducing the cost of catalyst".The details are as follows:（1）N-doped carbon materials modified by Fe and Co are used as bifunctional electrocatalysts.We have successfully prepared a three-dimensional honeycomb catalyst 3D Fe Co/N-C with carbon nanosheet stacking by using one-pot method and soft template method.This three-dimensional porous carbon network structure is the main reason that 3D Fe Co/N-C has good electrolyte permeability,large specific surface area and high conductivity.According to the performance test,the overpotential of 3D Fe Co/N-C in the alkaline OER process is only 0.3 V(current density is 10 m A cm^-2),and the half-wave potential in the ORR reaction is 0.81 V.In addition,we assembled the catalyst 3D Fe Co/N-C into the zinc-air battery and tested its stability cycle and power density.The test results showed that the 3D Fe Co/N-C catalyst had good stability.（2）Study on the performance of graded porous carbon catalysts.On the basis of the morphology regulation of carbon materials using single template in the previous chapter,this work,three templates are introduced into carbon materials to construct a richer and graded hole structure.The highlight of this experiment is that we dissolve soluble salts（sodium chloride,sodium carbonate,sodium silicate）with different particle sizes in the precursor solution.And finally,a porous carbon material 3D Co/N-C-BMS with large pores（≥50 nm）,mesopore（2-50 nm）,and micropores（≤2nm）was prepared.Holes of different grades form defects,which can not only increase the activity and density of active sites,but also greatly improve the specific surface area of materials.The electrochemical test results confirmed that 3D Co/N-C-BMS has excellent catalytic performance and stability,and has good practical value.