Study On Electrocatalytic Performance Of Pt Alloy Catalyst

The research and development of new energy technologies have promoted because of the energy crisis and environmental pollution,which has become a scientific issue of concerning to scientists all over the world.Fuel cells and metal-air batteries are highly efficient and environmentally friendly new energy technologies,which is inseparable from efficient and inexpensive cathode catalysts.At present,the precious metal platinum（Pt）is the most important catalyst for the cathode oxygen reduction reaction（ORR）,but its disadvantages limit the large-scale commercial application of the catalyst that including low abundance,high cost and susceptibility to poisoning severely.This thesis reduces the cost of the catalyst by introducing other cheap metals and Ptto form an alloy,thereby regulating the geometric structure and electronic structure of the catalyst,and improving the catalytic activity and stability of the catalyst in the ORR process.It mainly includes the following three parts:1.Preparation of PtPdCu ternary alloy by CTAB-assisted hydrothermal for electrocatalytic oxygen reduction and ethanol oxidation reactionMulti-element Ptalloy catalysts have the problems of controlling size during synthesis and unstable catalytic performance in acidic media.In this study,the surfactant cetyltrimethylammonium bromide（CTAB）was introduced,and the PtPdCu ternary alloy catalyst was prepared by the CTAB-assisted hydrothermal method with the size of 3-5 nm.The Pd and Cu atoms are introduced to modulate the geometric and electronic structure of metal Pt.So that the catalyst exhibits excellent ORR electrocatalytic performance,and better half-wave potential than the commercial Pt/C catalysts in acidic media.In addition,the catalyst exhibits higher resistance to CO poisoning and catalytic stability when catalyzing the ethanol oxidation reaction（EOR）.2.Preparation of PtMn/CNFs by electrospinning method for electrocatalytic oxygen reduction reactionThe ordered phase Ptalloy catalyst has higher catalytic activity stability than the disordered phase,while still facing greater difficulties in synthesis and preparation process.In this work,carbon-supported ordered Pt₃Mn catalysts were prepared by thermal annealing electrospun polyacrylonitrile（PAN）nanofibers containing Platinum（II）acetylacetonate/Manganese（III）acetylacetonate（Pt（acac）₂/Mn（acac）₃）.Compared with the counterparts,the ordered Pt₃Mn obtained at 950℃ exhibits a more positive half-potential and higher kinetic current density during the ORR process.Benefiting from the defined stoichiometry and crystal structure,the Mn atoms in Pt₃Mn intermetallic can modulate well the geometric and electronic structure of surface Ptatoms,endowing Pt₃Mn catalyst an enhanced ORR catalytic activity.Moreover,it also has a better catalytic stability and methanol tolerance than commercial Pt/C catalyst.3.Preparation of PtPdCu/CNFs by electrospinning for electrocatalytic oxygen reduction reaction and zinc-air battery performanceThe air electrode is a key factor that determining the performance of the zinc-air battery.The composition and microstructure of the catalyst significantly affect the oxygen reduction reaction of the air electrode.In this work,a PtPdCu ternary alloy catalyst was prepared by the electrospinning combined reduction carbonization method which supported on carbon nanofibers（CNFs）.The alloy catalyst particles with a particle size of6-10 nm which evenly distributed on the surface of the carbon nanofibers.With the good conductivity and pore-rich structure of carbon nanofibers,and the introduction of Pd and Cu atoms which modulated the geometric and the electronic structure of Pt,the PtPdCu/CNFs catalyst still has great ORR electrocatalytic activity and stability under the condition of low Ptcontent.The synthesized catalyst is assembled into a zinc-air battery,which has a peak power density of 2404 W g _Pt^-1 and a specific capacity value of 800 m A h g _Zn^-1,which is superior to commercial Pt/C catalysts.