Preparation And Properties Of Nitrogen-doped Carbon Nanotubes Supported Platinum Cobalt Oxygen Reduction Catalysts

Proton exchange membrane fuel cells as the most promising new,clean,environmentally friendly batteries much attention.In the proton exchange membrane fuel cell research,the cathodic oxygen reduction reaction rate is far lower than the anodic oxidation reaction rate.Therefore,the development of low cost,long life and good chemical properties of the cathode catalyst has important application value and theoretical significance.Carbon nanotubes with good water dispersibility and high specific surface area and conductivity,cobalt can reduce the investment cost of the catalyst,the noble metal platinum is the best,most commonly used cathode catalyst.Combined with the characteristics of the three,the development of carbon nanotubes as the carrier alloy catalyst is of great significance.In this paper,pure carbon nanotubes,polypyrrole-coated carbon nanotubes and nitrogen-doped carbon nanotubes as the carrier,the use of carbothermal reduction of cobalt-based catalyst preparation,comprehensive selection of various aspects of the performance of the carbon nanotubes supported cobalt Based catalyst and then controlling the reaction conditions immersed in the chloroplatinic acid solution to prepare a Pt-Co alloy catalyst.The effects of pure carbon nanotubes,polypyrrole-coated carbon nanotubes and nitrogen-doped carbon nanotubes on the morphology and electrochemical properties of Co/CNTs,Co/NCNTs@PPy and Co/NCNTs catalysts were investigated respectively The effects of volume of chloroplatinic acid solution,impregnation time and type of dispersant on the morphology and electrochemical performance of the alloy catalyst were investigated.The prepared cobalt-based catalysts and Pt-Co alloy catalysts with commercial Pt/C performance comparison,the main conclusions are as follows:Pure carbon nanotubes,large particle size,less active sites,poor dispersion performance.Nitrogen-doped carbon nanotubes introduced nitrogen-containing groups,with a larger specific surface area,is conducive to the metal cobalt loading and dispersion,can significantly enhance the binding capacity of carbon and cobalt metal.The cyclic voltammograms(CV)of Co/NCNTs catalysts showed a correctedoxygen reduction peak potential(-0.15V)and a larger oxygen reduction current density(1.63 m A/cm2);the linear sweep voltammograms(LSV)Correct starting potential(-0.02V)and greater limiting current density.The stability of Co/NCNTs is the best.Alloy catalysts with PtCo and CoPt3 structure,the reaction conditions are 12ml60 min C2H5OH,the best catalyst dispersion,the smallest particle size.The particles in the catalyst will be in the form of platinum particles,cobalt particles or spherical alloy.CV and LSV results show that: Platinum,cobalt has a good synergistic effect,electrochemical performance has been significantly improved,the transfer of electrons is about 3.44,to avoid the formation of intermediate products.Preparation of the alloy catalyst,which can effectively inhibit the loss of cobalt and make the chemical property more stable.Alloying catalysts have the same face-centered cubic crystal structure as commercial Pt/C.The number of transferred cobalt for the cobalt-based catalyst was2.80,that for the Pt-Co alloy catalyst was 3.44.Cobalt has a strengthening effect and the oxygen reduction ability of the alloy catalyst has been greatly improved.