Doped Carbon Material Supporting Precious Metal Nanoparticles For Fuel Cell Anode Electrocatalysis

Fuel cells cannot be commercialized for large-scale,due to factors such as excessive cost and poor stability of the electrocatalyst.At present,precious metal Pt-based catalysts are still recognized as the mainstream electrocatalytic materials.However,the Pt-based catalyst has poor anti-poisoning ability during the reaction,and the carrier is easily corroded and loses its effect,which will seriously affect the application of fuel cell technology.Therefore,it is necessary to develop and build a high-performance,low-cost electrocatalytic system.Among them,the development of a new type of doped material carrier loaded with high activity precious metal nanoparticles is a feasible solution which is a research hotspot in recent years.Alloys can be used as a promoting method to improve the performance of precious metal catalysts to improve catalytic activity and stability.And the catalyst support has an extremely important influence on the performance of the electrocatalyst.Researches find that the carbon composite material after functional modification has a good specific conductivity and a large specific surface area,which contributes to the dispersion of metal particles and enhances the synergistic effect with metal particles,greatly improving catalyst activity,stability and resistance to CO poisoning.Therefore,it is a feasible method to realize the commercialization of fuel cells by designing composite carrier-loaded high-activity noble metal nanoparticles for anode electrocatalytic oxidation reaction.The specific experimental content includes the following three parts:Part I:High Performance Nitrogen-Containing Carbon Supports Loaded Pd Nanoparticles for Glycerol Electrocatalytic OxidationAnthraquinone has advantages of good stability,high carbon content,low toxicity and easy availability which are considered as ideal carbon sources.The structure of C3N4approximates graphene and has good stability making it an excellent choice as a carrier material.In this study,a new type of nitrogen-doped carbon material was prepared by ball milling and segmental heat treatment.We prepared C3N4 with urea as the precursor,and doped with anthraquinone fabricated N-carbon support,and loaded Pd nanoparticles-loaded thereon,a new catalyst Pd/NC was prepared.In the field of new functionalized materials,nitrogen-doped carbon supports have been proven superiority to conventional carbon（Vulcan XC-72R）.At the same time,the electrocatalytic activity and stability of the Pd-based catalyst in the glycerol electrocatalytic oxidation were examined.The test results show that the peak current densities of Pd/NC and Pd/C catalysts are 368 mA mg^-1 and 253 mA mg^-1,respectively.Pd/NC has higher catalytic activity.And after 3000 s chronoamperometry,Pd/NC has a current density of 131 mA mg^-1 which is approximately 2.3 times higher than that of Pd/C(56 mA mg^-1)catalyst.After 500 cycles,the peak currents of Pd/NC and Pd/C catalysts are reduced to 90.8%and 85.7%,respectively.It further proves that Pd/NC electrocatalyst has better durability stability.Part II:High Performance Nitrogen-doped Carbon Supports Loaded Pd₃Fe Alloy Nanoparticles for Isopropanol Electrocatalytic OxidationContinuing the design of the previous chapter,we have designed another new nitrogen-doped carbon material as the electrocatalyst support.Anthraquinone is still used as a carbon source.Melamine is widely used as a nitrogen source due to its chemical stability and rich nitrogen content.Therefore,in this section,we obtained a nitrogen-doped carbon support（CN）by a similar method.The PdFe alloy was loaded on the CN by alcohol reduction method,and the Pd₃Fe/CN electrocatalyst was fabricated.In alkaline medium of isopropanol electrocatalytic oxidation,the peak current density of Pd₃Fe/CN catalyst is 513 mA mg^-1,which has higher catalytic activity than that of Pd/C(247 mA mg^-1)catalyst.And after 3000 s chronoamperometry,the current density of Pd₃Fe/CN is 45.2 mA mg^-1 which is approximately 2.9 times higher than that of Pd/C(15.6 mA mg^-1)catalyst.After 1500 cycles,the peak currents of Pd₃Fe/CN and Pd/C catalysts were reduced to 86.0%and 79.2%,respectively,which further proves that Pd₃Fe/CN electrocatalyst has better durability stability.And in anti-CO test,Pd₃Fe/CN catalyst has better resistance to CO poisoning.Part III:Fe/N Co-doped Carbon Support Loaded Ir₃Sn Alloy Nanoparticles for Urea Electrocatalytic OxidationIr-based catalysts are considered to be an alternative precious metal catalyst for electrocatalytic reactions.In addition,on the basis of the first two chapters of the paper,it is desirable to test the performance advantages of metal-nitrogen-doped carbon carrier structures,because the electronic structure and geometry of metals are regulated by non-metallic elements,thus affecting the catalyst.Therefore,in order to pursue more efficient electrocatalytic oxidation performance,in this section,by introducing an auxiliary metal Fe and a non-metal N component into the macroporous adsorption resin,a FeCN support is prepared by heat treatment,and the Ir₃Sn/FeCN catalyst is successfully prepared.The catalytic performance of urea in electrocatalytic oxidation was discussed.Compared to Ir/FeCN,Ir3Sn/C,Ir/C and Ni/C catalysts,the Ir₃Sn/FeCN electrocatalyst exhibits excellent electrocatalytic activity and good stability in urea electrocatalytic oxidation.The peak current density of the Ir3Sn/FeCN catalyst is 147.1 mA mg^-1,which has higher catalytic activity than that of the Ir/FeCN(31.2 mA mg^-1)and Ni/C(11.1 mA mg^-1)catalysts.And after 3000 s chronoamperometry,Ir₃Sn/FeCN has a current density of 13.7 mA mg^-1 which is much larger than the Ir/FeCN(4.1 mA mg^-1)and Ni/C(4.8 mA mg^-1)catalysts,further demonstrating that the Ir₃Sn/FeCN catalyst has better durability and stability.