Preparation Of Fe-Cu Bimetal Modified ZIFs-derived Nitrogen-doped Porous Carbon And Its Oxygen Reduction Performance In Full Ph Medium

In this paper,Fe-ZIF is obtained by introducing iron salt into the process of synthesizing ZIF-L in the water system,and then spreading it on the copper foil.The high temperature pyrolysis makes the Zn element in Fe-ZIF volatilize into a large number of vacancies,and at the same time the Cu atoms volatilized from the copper foil It is captured by a large number of vacancies and unsaturated sites of nitrogen-doped carbon materials,and finally Cu@Fe-N-C catalyst is obtained.Compared with the traditional method of introducing Cu element into the catalyst through the metal Cu salt solution,the introduction of Cu element through the Cu foil volatilization-carbon defect site capture strategy in this paper has obvious advantages such as lower cost,environmental protection,and less metal agglomeration.SEM results show that Cu@Fe-N-C has a petal-like hexagonal shape assembled in flakes,and the surface has a fold morphology,and its specific surface area is 1503.2 m2·g-1.The 0.34 nm crystal spacing in HRTEM corresponds to the(002)crystal plane of graphitic carbon,and 0.21 nm lattice fringes corresponding to the(Ⅲ)crystal plane of Cu also appeared,indicating the successful introduction of Cu.XPS results further verify the successful introduction of Fe and Cu elements in Cu@Fe-N-C,and the total percentage of pyridine nitrogen and graphite nitrogen is the highest compared to Fe-N-C,Cu-N-C,and N-C materials.The catalytic activity of oxygen reduction is very favorable.Raman results show that Cu@Fe-N-C has the highest ID/DG value compared to Fe-N-C,Cu-N-C,and N-C materials,which means that it has the highest density of defects.The research of catalysts with high-efficiency catalytic activity for oxygen reduction reactions in a wide pH range is crucial for the further development and application of new energy.The Cu@Fe-N-C catalyst obtained in this paper has shown excellent performance in the entire pH range.In an alkaline system,The E1/2 of Cu@Fe-N-C is 52 mV higher than that of 20%Pt/C(0.923 V vs 0.871 V),and has a higher performance in Onset potential and limiting current density.In addition,the catalytic activity of Cu@Fe-N-C in acidic electrolyte is comparable to that of 20%Pt/C.At the same time,it also shows good catalytic activity in neutral electrolyte,and the performance is significantly better than 20%Pt/C(0.756 V vs 0.656 V).In a wide range of pH systems,compared with 20%Pt/C,Cu@Fe-N-C has longer lasting stability and stronger methanol tolerance.In addition,Cu@Fe-N-C has a larger electrochemically active surface area and a lower impedance value than other comparative materials in the full pH system,which means that its active sites are more easily exposed during the oxygen reduction catalysis process of the full pH system.The electron conductivity is stronger,and it has a more ideal and fast kinetic process,so its oxygen reduction catalytic efficiency is higher.Cu@Fe-N-C shows excellent ORR performance in a wide pH range and can be called one of the best platinum-free catalysts for ORR so far.The zinc-air battery with Cu@Fe-N-C as the cathode catalyst can output peak power densities of 212.3 mW cm-2(6 M KOH system)and 118.2 mW cm-2(4 M NH4Cl+1 M KCl system),and has a good discharge performance and stability are better than those of a zinc-air battery with commercial Pt/C as the cathode catalyst.This article not only provides a high-performance Cu@Fe-N-C electrocatalyst for the oxygen cathode ORR process of zinc-air batteries and fuel cells,but also provides a simple,low-cost and environmentally friendly CuFe bimetallic nitrogen-doped catalyst material Synthesize a new strategy.