Study On Oxygen Reduction Catalysts With Highly Dispersed Metal Nanoparticles

High active and stabilized cathode catalyst is essential for the development of the fuel cell and metal-air battery.The AgCo@NC is derived by the wet impregnation of Ag into ZIF-67 precursor,followed by chemical reduction and a subsequent pyrolysis process under Ar atmosphere.SEM and TEM results show that Ag@ZIF-67 composite has the same microstructure as ZIF-67.After pyrolysis under Ar atmosphere,the particles of the product inherit the polyhedral structure,but the particles obviously shrink and particle size becomes small.With the temperature increasing,the product particles further shrink.The BET surface area of the AgCo@NC-600 material is 245.93m²;XPS indicates that the main form of N is pyridinium and graphite nitrogen.The electrochemical test results show that AgCo@NC-600 exhibits the strongest oxygen reduction catalytic activity,and its catalytic performance is similar to that of commercial Pt/C catalyst.In order to investigate the influence of silver doping on the ORR electrocatalytic activity of La_0.8-xSr_0.2Ag_xMnO₃,La_0.8-xSr_0.2Ag_xMnO₃（x=0,0.05,0.08,0.15）was prepared by sol-gel method.SEM results show that the materials are nanoparticles.XRD results show that the unit cell constant of the material is changed.Electrochemical test results show that doping excess Ag increase the ORR activity of the La_0.8-xSr_0.2Ag_xMnO₃.In order to investigate the change of the ORR electrocatalytic activity,Ag was reduced the surface of the La_0.75Ag_0.05Sr_0.2MnO₃ and La_0.65Ag_0.15Sr_0.2MnO₃ by the H₂reduction method.SEM results show that the microstructure of the materials are unchanged.XRD results show that the crystal structure of the materials have changed.The electrochemical test results show that the ORR catalytic activity of La_0.75Ag_0.05Sr_0.2MnO₃-R and La_0.65Ag_0.15Sr_0.2MnO₃-R decreases after H₂ reduction,indicating that the H₂ reduction method does not enhance the ORR catalytic activity.Figure28;Table9;Reference 150.