Template Synthesis Of Heteroatom-Doped Porous Carbon Materials And Electrohemical Properties Of Heteroatom-Doped Carbon

The energy crisis has made the development of new energy sources one of the most urgent tasks at present.Fuel cell has received world-wide concern due to its many advantages such as high energy efficiency,environmental friendliness and sustainability,etc.The electrode material of traditional fuel cell is composed of platinum、ruthenium and iridiumnoble metal catalysts.Although they has high catalytic efficiency,its limited reserves,high price and poor stability block large-scale commercialization application of fuel cells.Therefore,it is necessary to prepare an electrocatalyst with high catalytic activity,low cost and good stability.Currently,materials with high active sites include metal-free heteroatom（N、P、S）doped carbon materials,transition metal and nitrogen-doped（M-N-C,M=iron,cobalt,molybdenum,nickel,niobium）materials,metal oxides,transition metal phthalocyanines（porphyrins）and their composites with carbon nanomaterials.Among them,transition metal and nitrogen-doped carbon nanomaterials have become a hot topic because of their high activity and excellent stability for oxygen electrode reaction.This paper is composed of three parts as follows:（1）A novel 3D porous nitrogen-doped carbon（Fe₃C/NC）supported on Fe₃C nanoparticles was synthesized by a hard template method and used as an efficient oxygen reduction catalyst in alkaline medium.Experimental results show that the electrocatalytic activity of the catalyst depends on the temperature of thermal decomposition and the composition of precursors.The catalyst obtained at pyrolysis temperature of 1000°C,named Fe₃C/NC-1000,has the best electrocatalytic activity.The Fe₃C/NC-1000 even has more positive onset and half-wave potentials than Pt/C（20 wt.%Pt）.It also shows better methanol cross-reaction tolerance.After 3000 cycles of cyclic voltammetry,the onset and half-wave potentials of the Fe₃C/NC catalyst are nearly unchanged,showing superior durability.（2）A novel zinc,cobalt,sulfur and nitrogen co-doped hollow carbon spheres material（Zn@Co/NSC）was synthesized by a microemulsion method（soft-template method）,and utilized as an efficient electrocatalyst for oxygen reduction in both acidic and alkaline media.The method combines the spherical structure of microemulsion with the growth characteristics of MOFs to prepare the Zn@Co/NSC catalyst with hollow spherical structure.The optimized Zn@Co/NSC-800（the material pyrolyzed at 800°C）catalyst has the onset potentials of 1.0 and 0.882 V vs RHE for ORR in alkaline and acidic media,respectively.In addition,the obtained catalyst has good stability and good methanol resistance.