Preparation And Electrocatalytic Performance Of Platinum Based Anode Catalysts For Direct Methanol Fuel Cells

As a new type of energy conversion device,Direct methanol fuel cell can efficiently convert the chemical energy in methanol directly into electricity.It has the advantages of safe fuel storage,safe transportation,abundant raw materials,fast start at low temperature,flexibility and convenience,and is green and pollution-free.It fits perfectly with the current energy shortage and serious ecological and environmental problems,and then received widespread attention.However,the most efficient catalyst for Direct methanol fuel cell was the platinum-based catalyst,whose high cost severely limits its large-scale production,therefore,the preparation of anodic catalysts with high catalytic activity,high stability and low cost is the research hotspot nowadays.In this paper,transition metals Ni and Co were introduced into Ptcatalyst to improve the performance of the catalyst through the synergistic effect of bimetals,and carbon nanotubes were modified to increase the specific surface area of the support,a series of Pt-based catalysts were prepared and characterized by electrochemical detection and morphology.(1)PtNi/CNTs and PtCo/CNTs catalysts were prepared by impregnation reduction with transition metals,it was found that there was a synergistic effect between Ptand transition metal.The introduction of Ni and Co decreased the average particle size of metal particles,increased the dispersion of metal nanoparticles on the support,and increased the active sites of the catalyst,so as to improve its catalytic performance.When Pt:Ni=1:1and Pt:Co=1:0.2,the catalyst showed the highest current density and the best stability.(2)Pt/CNTs-C catalyst was prepared by combining carbon black with carbon nanotubes of different morphologies to form composite support,which formed a unique space configuration.The composite carrier improves the surface utilization of the carbon carrier and makes the nano-metal have more adhesion points.When the ratio of concentrated sulfuric acid to concentrated nitric acid was 3:1,the maximum specific surface area was 282.13 m~2/g.When carbon nanotubes:carbon black=1:0.25,the catalyst showed the best catalytic performance.(3)PtNi/CNTs-C and PtCo/CNTs-C catalysts were prepared by combining metal components with mixed carbon support,the results showed that the peak current density of PtNi/CNTs-C was 73.36 m A/cm~2,and that of PtNi/CNTs-C was 86.35 m A/cm~2.Both have high current density,low impedance and high stability.It is shown that the synergistic effect of Ptand transition metal components and the unique space configuration of the mixed support can improve the catalytic performance of Pt-based catalysts for Methanol.The morphology and structure of the composite catalyst were characterized by SEM,TEM,XRD and XPS,the effects of temperature,scanning rate,amount of reducing agent and KOH concentration on the electrocatalytic performance of methanol were studied by cyclic voltammetry.The results showed that the two metal catalysts exhibited good dispersion and particle size was about 20 nm under TEM,and the surface Ptof PtNi/CNTs-C and PtCo/CNTs-C catalysts was larger than that of Ptcatalysts,it shows that it has more active sites.The electrochemical test showed that the higher the temperature and the scanning rate,the greater the current density,and the current density increased first and then decreased with the concentration of reducing agent and KOH,when the concentration of alkali is 1mol/L and the amount of reducing agent is 10 times the theoretical value,the current density reaches the maximum.Compared with the two catalysts,PtCo/CNTs-C catalyst has better performance.