Preparation And Electrocatalytic Properties Of Pt(Pd)-Based Porous Nano-alloy Catalysts

Because Pt and Pd have excellent electrocatalytic oxidation ability for methanol etc,they are the most widely used catalysts for direct methanol fuel cells.But the resources of Pt and Pd are scarce and expensive,hindering the commercialization of fuel cell.In addition,Pt can be easily poisoned by CO intermediates in the process of electrochemical oxidation,which can reduce the catalytic activity.Therefore,it's significant to develop the fuel cell catalyst with low Pt and Pd load to improve the catalytic activity and anti poisoning ability.In this paper,a series of Pt and Pd based alloy catalysts with special morphologies were prepared by reducing the amount of noble metal and increasing the specific surface area of the catalyst.By SEM,TEM,physical adsorption analyzer,the materials were characterized.And the electrocatalytic performance of the catalysts by electrochemical tests for methanol and formic acid was analyzed:1.In the absence of surfactant,highly homogeneous multipod Pd3 Cu nano alloy catalyst was synthesized.And the particle size is about 500 nm.By XPS,XRD,EDS analyzing,The ratio of Pt to Pd is 3:1.Compared with the commercial Pd black,its performance is pretty good.2.The 3D network structure Pd-Cu alloy was prepared by using hydrothermal method.Using ethylene glycol to restore the precursor,different Pd-Cu ratio is controlled by changing the amount of precursor Na2PdCl4 and CuCl2·2H2O.The specific surface area of the alloy was analyzed by means of physical adsorption.The specific surface area of Pd51Cu49 and Pd76Cu24 were 20.7 m2·g-1 and 10.4 m2·g-1,respectively.Electrochemical tests show that Pd51Cu49 has a larger electrochemical active area.The electrocatalytic performance of formic acid is better than that of Pd black.3.The spherical PtPdCu alloy with porous structure was synthesized by using block copolymer P123 as the structure directing agent.The specific surface area is 86.9 m2·g-1.This material is not only has high gas permeability and mass transfer ability,but also make up the material and ion long transport distance of traditional porous structure,greatly reduces the overpotential,which makes the electrode surface dynamic better.4.In order to further reduce the amount of precious metals and reduce the cost ofcatalyst production.We have prepared PtSnCu alloy catalyst with porous structure.The addition of Sn can produce adsorbed OH on the surface of catalyst,which can improve the conversion efficiency of CO2.Moreover,with the increase of the number of electrochemical test,Cu can be dissolved gradually,forming a rich Pt catalytic surface,exposing more catalytic active sites,significantly enhancing the catalytic performance of the catalyst.It is a promising alloy catalyst.