Preparation Of Low Platinum Multi-component Nanocrystals By Seed Method And Study On Their Electrocatalytic Properties

Fuel cell is a new energy device with many advantages such as high energy density,green and high efficiency.In recent years,platinum(Pt)-based nanocatalysts have received widespread attention due to their broad application prospects in fuel cells.Among them,preparing Pt-based catalysts with high atom utilization efficiency can induce more active sites between Ptatoms and participating molecules,thereby improving mass activity.In addition,engineering design of the surface structure of Pt-based nanocrystals provides an effective way to develop electrocatalysts with greatly enhanced catalytic activity.In short,reducing the cost of the catalyst and improving the activity of the catalyst are of great significance to the development of fuel cells.This paper uses the seed method to prepare low-platinum multi-element nanocrystals as the main research route.Through a two-step synthesis method,regular PtCu octahedrons and PdCuPticosahedrons are used as seeds to prepare low-platinum multi-element nanocrystals with controllable components.The low-platinum multi-element nanocrystals not only have excellent electrocatalytic activity,but also reduce the usage of Ptand Pd,and reduce the production cost of the catalyst.1.Using regular PtCu octahedrons as seed crystals,through a two-step method in a system where N,N-dimethylformamide is used as a solvent,platinum acetylacetonate is added to oxidize metallic copper at 115°C to form a hollow octahedral structure.In addition,theCucomposition can also be adjusted according to time.In the electrochemical study of oxygen reduction reaction(ORR)in alkaline environment,the area activity and mass activity of the hollow PtCu/C octahedron are30.5 times and 18.5 times that of Pt/C,respectively.After 10,000 cycles of scanning,the mass activity(MA)of the hollow PtCu/C octahedron is 53.7 times that of Pt/C.In addition,the hollow PtCu/C octahedron has high resistance to CO poisoning.Research on the catalytic methanol oxidation of hollow PtCu/C octahedrons shows that the area activity(SA)and MA fraction of hollow PtCu/C are 10.25 and 5.87 times higher than commercial Pt/C.2.With regular PdCuPticosahedron as seed crystals,in a two-step method in a mixed system of N,N-dimethylformamide,water PVP,and potassium chloride,concentrated nitric acid was added to oxidize copper at 60? to form PdCuPticosahedron with controllable composition.In the ORR electrochemical study in alkaline environment,the optimum MA of PdCuPt/C icosahedron is 21.0 times and51.0 times that of Pt/C and Pd/C,respectively.Studies in ORR stability show that after 10,000 cycles of scanning,the mass activity of PdCuPt/C icosahedron is 38.2times and 96.7 times that of Pt/C and Pd/C,respectively.