Research On Preparation And Catalytic Properties Of Gold Platinum Nanoparticles By Magneto-electrodeposition

Lithium-air batteries, a promising batteries, have a high theoretical specific energy. As the raw materials in positive reaction, oxygen can be provided by air continuously. For non-aqueous lithium-air batteries, insoluble product would appear during discharging, which would decrease the cycling performance and specific capacity. Au-Pt alloy could catalyze the positive reaction and increase the insolubility of production. But the traditional Au-Pt alloy catalyst have the problems of uniting, oversized grain diameter and falling of the carrier. Nano-catalyst prepared by traditional electro-deposition have large grain size, though it could be distributed uniformly. High magnetic field could influence the process of electrocrystalization and promote the generation of nano-construction. However, the studies of preparing catalyst by magneto-electrodeposition cannot be seen frequently. Consequently this thesis concentrate on preparation of Au-Pt catalyst by magneto-electrodeposition.Technological parameters were optimized and Au-Pt catalysts of50nm and30nm grain size were prepared by direct current electrodeposition and pulse electrodeposition under high magnetic field respectively. Catalysts grew in3D easily, and had high roughness and high rates of high-active sites in Vertical magnetic field, while they were distributed uniformly, and had smaller grain size and high specific surface area in parallel magnetic field.Theoretical model of magneto-electrodeposition process was built, which explained how the magnetic field influenced the process of electrodeposition. On one hand, under vertical magnetic field metal cation moved in helix in the area perpendicular to the negative surface, which weakened the concentration polarization. On the other hand, under parallel magnetic field matal cation moved in gyration in the area parallel to the negative surface, which promoted the concentration polarization.Au-Pt alloy electrodeposition belonged to non-canonical co-deposition. There was diffusion control in process of electodeposition. The nucleation mechanism was more likely progressive.