Study On The Preparation And Structure-activity Relationship Of Nitrogen Polymer-based M-N/C Catalyst For Oxygen Reduction

The proton exchange membrane fuel cell (PEMFC) has many advantages, andthus received extensive attention of scholars, due to the high cost of Pt, thecommercial development has been restricted. In order to reduce its costs, to achievethe commercialization of fuel cells, researchers have been trying to develop newcatalysts to make a breakthrough. Among them, the cathode oxygen reductioncatalysts with non-noble metal become a research hotspot at home and abroad.The preparation of Fe-PPy/HCF/C composite catalyst precursor was byimmersion method. We doped K4[Fe(CN)6] into the polypyrrole (PPy) chain structurewhich was in situ polymerization on the surface of Bp2000. Then the precursor wastaken high temperature heat treatment to get a new kind of oxygen reduction reactioncatalyst with non-noble metal, named Fe-PPy/HCF/C. And we optimized the factorswhich were related to the preparation of this catalyst, such as protective atmosphere,heat treatment temperature, doping amount, etc. The research results showed that thecatalyst got the most excellent electrochemical activity when the heat treatment wasunder900℃in N2atmosphere and the mass ratio of K4[Fe(CN)6]and pyrrole (Py)was1:5. Element analysis and Raman test showed that doping was beneficial to theimprovement of N element of catalyst,so as the electrochemical activity.We used aniline to modify phenolic resin. Then we used one-step method tosynthesis non-noble metal catalyst with ordered pore structure. Using the testmethods such as element analysis, TEM to get the element content and structuremorphology of the catalyst, while using the cyclic voltammetry and linear sweepvoltammetry to test the oxygen reduction performance and stability of the catalyst.The research results showed that the catalyst got the most excellent electrochemicalactivity when the Fe content in the catalyst was7%and the amount of aniline was2.5g. At the same time, its starting voltage was0.87V,and the wave potential was0.67V. Element analysis showed that the mixed aniline can significantly improve theN content in the catalyst, which can improve the activity of catalyst. After1000CV acceleration, the half wave potential of the catalyst was only decreased of0.02, it’sbetter than that of commercial Pt/C catalyst. The electron transfer number for oxygenreduction reaction of the Fe-N-C catalyst was3.89by calculating, while the exchangecurrent densityi0in the process of oxygen reduction reaction was1.24x10-9A/cm2,which was close to the level of commercial Pt/C catalyst.