Preparation And Performance Study Of Low Platinum Loading Fuel Cell Catalysts

With the rapid development of the society and economy,people's demand for energy is also increasing.However,over-exploitation of fossil energy will not only lead to scarcity of resources,but also cause certain damage to the environment.Therefore,reducing the use of fossil fuels and exploring the development of sustainable renewable energy is of great significance to the development of society.Hydrogen proton exchange membrane fuel cell(PEMFC)has attracted wide attention due to its high power density,fast start-up,lower working temperature and environmental friendliness.However,the cathodic oxygen reduction reaction(ORR)is a slow kinetic process and requires a catalyst to accelerate this reaction.So far,the most effective ORR catalyst for PEMFC is still Pt-based catalyst.The scarcity of platinum resources and their high prices are a major factor in the higher cost of PEMFC,which severely limits the commercial application of PEMFC.Reducing the loading of precious metal Pt and improving its resource utilization efficiency and catalytic performance is already a key point in the commercialization process of PEMFC that needs to be solved urgently.In order to solve the above problems,this article first selects different platinum salt precursors(H₂Pt Cl₆,Pt(C₅H₇O₂)₂and Pt(NH₃)₄(OH)₂),and adopts a simple impregnation method to adsorb on the carrier.Carbothermal reduction in an atmosphere to prepare a platinum-carbon catalyst with low-platinum loading.Next,different supports are selected as graphene oxide(GO)and conductive carbon black(BP2000).The BP2000 was pre-oxidized and the same preparation method was used to prepare a platinum-carbon catalyst with low platinum loading.SEM,TEM,XRD,XPS and other instruments were used to characterize the morphology and composition of the catalyst.The CHI760C electrochemical workstation was used to conduct electrochemical testing of the catalyst.The following conclusions were obtained based on the results obtained,the main contents of this article are as follow:(1)Among the low-platinum catalysts prepared with different precursors,the catalyst prepared with Pt(NH₃)₄(OH)₂as the precursor exhibits the best ORR activity.Among the catalysts prepare with different supports,the catalysts prepared with pre-oxidized BP2000as the support exhibited higher electrocatalytic activity.(2)The use of Pt(NH₃)₄(OH)₂as the precursor exhibits high activity due to the strong relationship between the Pt(NH₃)₄²⁺in the precursor and the negatively charged oxygen-containing groups on the edge of the carbon support and the defect.The electrostatic adsorption makes the Pt(NH₃)₄²⁺/C composite material difficult to agglomerate and grow during the carbothermal reduction process,and has a good control over the size and distribution of platinum nanoparticles.(3)Conductive carbon black BP2000 itself has good conductivity.After the carbon powder is pre-oxidized,it has a larger specific surface area and more negatively charged oxygen-containing groups.The sufficient anchoring of the platinum precursor makes The platinum nanoparticles in the catalyst are more uniformly dispersed and have a smaller size(?3nm),so the catalyst exhibits excellent ORR activity.(4)Pt(NH₃)₄(OH)₂will form pyridinic N active sites during the pyrolysis process.The synergistic catalysis of pyridinic N and platinum nanoparticles also makes Pt/C-N more effective.High catalytic activity.Electrochemical test results show that Pt/C-N has a higher half-wave potential and greater current density than commercial platinum carbon.According to calculations,Pt/C-N The mass specific activity is three times that of commercial platinum carbon.