Preparation Of Mesoporous Carbon Nanofibers And Their Properties For Electrochemical Catalysis

With a pore size in the range of 2 to 50 nm,mesoporous materials play a pivotal role in many fields such as catalyst,energy storage,and biological environment due to their extremely high specific surface area,adjustable framework and long-range orderly porous structure.Mesoporous carbon nanofibers(MCNFs)have more novel and unique characteristics while maintaining the properties of carbon nanofiber materials,such as providing channels for rapid transfer of reactants,increasing the reaction contact area,and etc.Therefore,the research on mesoporous carbon nanofibers is valuable and meaningful.Based on the point,mesoporous carbon nanofibers with high specific surface area and large pore diameter were successfully prepared through a simple method,and were used as the catalysts for oxygen reduction reaction(ORR)in this work.The main research contents and results were as follows:(1)The atom transfer radical polymerization approach was used to prepare amphiphilic block copolymer(polystyrene-block-polyacrylonitrile,PS-b-PAN).The molecular weight of the obtained PS-b-PAN was 30997.The molecular weight distribution of this block copolymer was very uniform,and the polydispersity coefficient was only 1.16.(2)The N and S co-doped mesoporous carbon nanofibers(NS-MCNFs-T,T=800,900,1000?)with uniformly arranged pores were prepared by electrospinning and post-processing.The NS-MCNFs-900 had a large mesoporous size(12.1 nm)and a high specific surface area(594 m² g^-1).When tested in 0.1 M KOH solution,NS-MCNFs-900 showed superior ORR activity.The half-wave potential was 0.81 V(vs.RHE),the limiting current density was 4.97 m A cm^-2.NS-MCNFs-900 also showed high long-term stability and methanol tolerance.(3)The N?S and Co co-doped mesoporous carbon nanofibers(Co-NS-MCNFs-T,T=800,900,1000?)were prepared by electrospinning,in-situ synthesis and post-processing.Among them,Co-NS-MCNFs-900 had the highest specific surface area(742 m² g^-1)and large mesoporous pore size(10.8 nm).When tested in O₂-saturated 0.1 M KOH solution,Co-NS-MCNFs-900 exhibited superior electrocatalytic activity for ORR.The half-wave potential and limiting current density was0.83 V(vs.RHE)and 6.19 m A cm^-2,respectively.Even in 0.1 M HCl O₄,Co-NS-MCNFs-900 still showed better stability and methanol tolerance than commercial Pt/C.