Study Of Platinum Based Alloys And Its Surface Catalytic Performance

Fuel cell has many advantages, such as wide raw material sources,high efficiency of energy conversion and environmentally friendly. As a new energy alternative to traditional fossil fuel, the fuel cell has received wide attention across the world.As the most widely used fifth-generation fuel cell, Proton exchange membrane fuel cell has the longest life, the lowest temperature. It is standing at the edge of commercial development. However, the overloading of Pt in the cathode catalyst is a bottleneck in the development of all existing fuel cells. At present, the improvement of Pt catalyst at home and abroad mainly focused on two aspects, one is to reduce the size of Pt-based catalyst particle size, the other is to add other mental elements to the Pt catalyst by various physical and chemical means to make the Pt catalyst alloying, or to disperse Pt into other transition metals, metal alloys, core-shell structures or conductive oxides to form a mixture or alloy. In this paper, the physical properties of the Pt3M alloy system and the mechanism of oxygen reduction reaction on the Pt-skin/Pt3M (111) surface have been studied using the first-principles calculations based on the density functional theory.Firstly, the physical properties of Pt3M alloy system were calculated.In order to ensure the accuracy of the calculation process, the convergence test and geometry optimization of the structure of the model were used. Then, the structural stability, elasticity and electronic structure of the Pt3M alloy system are discussed by the first-principles calculation method. In Pt3M, the M elements are alkali metals, alkaline earth metals,the main group elements and 3d, 4d transition metals, a total of 38 kinds of elements.Secondly, the oxygen reduction mechanism of Pt-skin/Pt3M(111)surface was calculated. The surface model used was a (1x1) surface supercell, with a 4-atom slab and a vacuum layer of 11 A. This research also exchanged one Pt atom on the surface and one M atom on the subsurface, so that the Pt accounting for 100% on the surface and 50% on the subsurface respectively. Firstly, the adsorption and dissociation of O2 on the surface were studied, and then the intermediates and path of the oxygen reduction reaction were studied.