Synthesis And Properties Of Nitrogen(Sulfur) Doped Carbon-based Materials For Oxygen Reduction Reaction

Electrochemical oxygen reduction?ORR?is the core reaction in fuel cells.Unfortunately,the ORR process shows slow kinetics,greatly affecting the performance of the whole energy systems.Therefore,the design and development of oxygen reduction reaction?ORR?catalysts with low cost,high activity and strong stability is of great significance for the application of fuel cells.Doped carbon-based materials are one of the most effective candidates for oxygen reduction catalysts due to their high electrical conductivity,high stability,excellent anti-poisoning ability,and efficient ORR performance.Besides,metal sulfides are also used as ORR catalysts due to their low cost and high activity,as well as excellent ORR performance.Thus,in this paper,we focus on the doped carbon material and metal sulfides.The nitrogen?sulfur?doped carbon-based catalysts with morphology,structure and composition was obtained by using different preparation methods.The research content is as follows:?1?Etched N-doped porous carbon?E-NPC-t,t for etch time?was successfully synthesized and optimized by the combination of template method and NH₃etching,with pyrrole as nitrogen and carbon source,silicon dioxide as hard template.The results show that the addition of Si O₂template and NH₃etching can increase the specific surface area of carbon materials,and expose more effective active sites.Compared to other counterparts,the E-NMC-5 shows optimized morphology,structure and composition.Thus,it exhibits superior ORR performance.?2?Porous core-shell Fe_1-xS@N,S co-doped carbon(Fe_1-xS@NSC-t,t for etching time)was synthesized by Fe₃O₄nanospheres as template and pyrrole as carbon and nitrogen sources,respectively.The Fe_1-xS@NSC-24 possesses optimized structure defect,specific surface area and doped heteroatoms configurations,thus leading to outstanding catalytic activity and cycling stability towards ORR.?3?Using pristine graphite and carbon nanotubes?CNT?mixture as initial carbon source.The N,S-co-doped carbon nanotubes/graphene/Mn S ternary hybrid?NSCNT/NSG/Mn S?was achieved by the combination of effective exploitation of residual Mn and S species and reducibility of carbon under high temperature.The NSCNT/NSG/Mn S can not only effectively disperse Mn S nanoparticles,but also possess large specific surface area,high N content and unique 3D architecture.Thus,the obtained 3D NSCNT/NSG/Mn S exhibits superior ORR performance.