Preparation And Electro-catalytic Performance Of Carbon-based Material For Oxygen Reduction Reaction

Zinc-air battery is a green and power-efficient technology,and it has been extensively investigated during the last decade.However,several problems are still hindering its commercial scale application,and one of them is the sluggish kinetics of electrocatalysts for cathodic oxygen reduction reaction(ORR).Traditional platinum catalysts which face massive problems like low abundance,easily poisoned,can't meet the requirments of cathodic catalysts for the application in zinc-air battery.According to the recent researches,carbon-based material is demonstrated to be a promising alternative of platinum as an efficient ORR catalysts despite of the relative low device performance.(1)Mesoporous carbon-based nanomaterial m-FeSNC is prepared by the pyrolysis of poly o-phenylenediamine on the assembled silica nansphere templates.Ferric chloride and ammonium persulfate are selected as the polymerization initiators.Due to the strong chemical interaction between the iron source and the o-phenylenediamine monomer,the iron species are evenly dispersed in the carbon skeleton;the incorporation of sulfur prevents the formation of well crystalline graphite species and thus facilitates the formation of Fe-Nx active sites;the construction of mesoporous structures helps the catalyst to expose more active sites and promote the mass transfer.M-FeSNC shows a half-wave potential of 0.904 V in 0.1 M KOH electrolyte with good stability toward ORR.Assembled zinc-air battery equipped with m-FeSNC has a peak power density of 221 mW cm-2,which surpassesthat of commercial platinum carbon.(2)A layered carbon-based nanomaterial was prepared by using layered graphitic carbon nitride(g-C3N4)with high nitrogen content as a template.Iron atoms are pre-stacked on the hexadazine structure unit of g-C3N4.Then,Fe,N co-doped carbon nanosheets(FeN-CNS)was prepared by the encapsulation of glucose and the successive pyrolysis.The special chemical structure of g-C3N4 is beneficial to retain the dispersion of iron.Besides,the confinement effect from the assembling of carbon layers also contributes to the contruction of uniformly dispersed Fe-Nx active sites.FeN-CNS show superior ORR activity and stability in both half-cell and zinc-air battery.In this thesis,two new carbon-based nanomaterials have been developed.These two materials have good electrocatalytic ORR activity and have potential applications in zinc-air batteries.The research results are of reference value for the development of ORR electrocatalysts.