Preparation And Properties Of Silver-Based Electrocatalyst For Oxygen Reduction Reaction In Alkaline Media

In order to curb environmental pollution and climate change,China has formulated Double Carbon Policy of carbon emissions peaking and carbon neutrality,and changed the energy utilization and structure to achieve the goal of"zero emission"of greenhouse gases.Hydrogen energy is known as the ultimate energy.It is clean and efficient.Fuel cell is one of the most important energy devices in the process of hydrogen energy use.Oxygen Reduction Reaction（ORR）occurs at the cathode side of the fuel cell,and its reaction rate is slower than that at the anode side.The ORR reaction rate determines the output power of the fuel cell.Pt-based catalysts is the most widely used catalysts in ORR reaction,but its high cost and small earth reserves greatly limit its commercialization process.Ag-based catalysts show better ORR catalytic activity under alkaline conditions and can be used in the cathode of anion exchange membrane fuel cells.In this paper,silver catalysts supported by single metal and bimetal oxides were prepared by the combination of Ag and transition metal oxides,and the combination of Ag and transition metal oxides was further regulated to improve the performance of the catalyst,and showed good performance in the test of anion exchange membrane fuel cells.The specific research content of this paper is as follows:（1）A series of 3d transition metal oxide carriers were prepared by calcination method,and the Ag-based composite catalyst was obtained by loading Ag at room temperature.Ag/MnO showed the best catalytic performance,and its ORR half-wave potential(E_1/2)reached 0.829 V（vs.RHE）,which was mainly attributed to the high oxygen adsorption capacity of Mn.Ag/Ni MnO catalyst was prepared by introducing a second transition metal element.Thanks to the synergistic effect between metals,the Ag/Ni MnO E_1/2was increased to 0.840 V,and after 4000 cycles of accelerated aging test,the Ag/Ni MnO E_1/2 was only reduced by 16 m V.（2）Ag CuMnO_x/C catalyst was prepared by hydrothermal method.By changing the composite mode of Ag and transition metal oxides,Cu,which is similar to the crystal structure and lattice constant of Ag,was introduced,so that Ag,Cu and Mnin the prepared nanoparticles were dispersed more evenly,and the nanoparticles were not easy to agglomerate.In the rotating disk electrode test,the E_1/2 of Ag Cu MnO_x/C is 0.820 V,and the Tafel slope is 40 m V dec^-1,where E_1/2 is 58 m V higher than Ag/C.The area activity of Ag Cu MnO_x/C at0.85 V was 1.19 m A cm _Ag^-2,which was 164%higher than that of Ag/C.Ag Cu MnOx/C also has good stability.After 4000 cycles of accelerated aging experiment,E_1/2 only decreased 8 m V.Finally,the prepared catalyst was applied to the anion exchange membrane fuel cell,and its peak power density reached0.768 W cm^-2.