Preparation And Properties Of Non-Noble Metal-Doped Carbon Catalysts With Ionic Liquids As Heteroatom Doping Sources

As a new type of energy source,proton exchange membrane fuel cells can bypass the Carot cycle and make efficient use of energy with a clean and environmentally friendly process.However,the high cost of the catalyst has limited the promotion and production of proton exchange membrane fuel cells.The main reason for the high catalyst cost is the use of platinum-based catalysts.As a precious metal,platinum does have its advantages in catalytic performance,but its high cost and easily being toxic have become the key to the commercial production of proton exchange membrane fuel cells.Therefore,fundamentally developing low-cost,high-performance non-precious metal catalysts that can completely replace platinum has become a top priority.In this paper,a non-noble metal doped carbon catalyst with high catalytic performance was prepared by using low cost,easily prepared and structurally modified ionic liquids and polymeric ionic liquids as heteroatom doping sources.The main work is as follows:1.Fe-N(IL)/C catalyst was prepared by solution blending and high temperature pyrolysis with the ionic liquids([Emim]Br,[Emim]BF4,[Emim]PF6)as doping source and FeC13 as the central coordination atom.We studied the influence of many factors on the formation of the active site of the catalyst during the preparation process.Studies show that the choice of heteroatom doping source,the temperature of thermal decomposition and the content of FeCl3 can affect the activity of the catalyst.when[Emim]Br is used as the ionic liquid,750? is selected as the thermal decomposition temperature,and the molar ratio of the ionic liquid to FeCl3 is 1:2,the performance of the catalyst is optimized,and more pyridine nitrogen and graphite nitrogen can be formed in the catalyst,so that the initial reduction potential reaches 0.795 V(vs.RHE).2.We were prepared a series of Fe-N(PIL)/C catalysts by two-step method of solution blending and high-temperature pyrolysis with polymeric ionic liquid P[VEIM]Br as a heteroatom doping source,multi-walled carbon nanotubes as support,and Fe(NO3)3·9H2O as metal coordination atoms.We also investigate the effects of thermal decomposition temperature and the amount of polymerized ionic liquid on the activity and stability of the catalyst.Experiments show that when the thermal decomposition temperature is 800? and the mass ratio of multi-walled carbon nanotubes to polymerized ionic liquid is 1:7.5,the activity of the catalyst is the best and the highest value can reach 0.80V(vs.RHE).3.A series of Fe-N(PIL/DCD)/C catalysts were prepared by the two-step method which are solution blending and high-temperature pyrolysis with Polymeric ionic liquid P[VEIM]Br and dicyandiamide DCD as composite nitrogen source,multi-walled carbon nanotubes as carriers,and Fe(NO3)3·9H2O as the metal coordination atom.Physical and electrochemical characterization showed that the addition of DCD effectively increased the nitrogen content of the catalyst and the proportion of graphite nitrogen,making the catalyst reach the highest initial reduction poten,tial to 0.85 1V with a pyrolysis temperature of 800°C and mMWCNTs:mPIL:mDCD=1:7.5:3.75.The number of electrons transferred which is 3.63 indicate that the catalyst mainly catalyzes the oxygen reduction reaction in the form of four electrons.