Preparation And Electrocatalytic Performance Of Polymer Derived N-Doped Carbon Materials For Oxygen Reduction Reaction

Nitrogen-doped carbon(NC) materials are currently considered to be one of the most promising electrocatalysts towards oxygen reduction reaction(ORR)because of their high catalytic activity,less sensitivity for methanol cross-over and excellent stability.N-containing organic porous polymers have the characteristics of high specific surface area,developed porous structure,high skeleton strength,and relatively high N contents,and moreover,N atoms are fixed homogeneously in the polymer networks,which make them a prior choice of precursors for the synthesis of NC catalysts.In this thesis,organic porous polymers with relatively high N contents were used as precursors to prepare nonprecious metal-N doped carbon(M-N/C)catalyst and metal-free NC catalyst.Meanwhile,the electrocatalytic performances of the two type catalysts towards ORR were systematically investigated.The main research contents were shown as follows:(1)Preparation and ORR electrocatalytic performance of Fe-N/C catalyst based on PCPAT.Firstly,organic porous polymer,PCPAT,was synthesized by trimerization of tri(p-cyanophenylamino)[1,3,5]triazine(CPAT)using anhydrous Zn Cl2 as catalyst at high temperature.And then,the Fe-N/C catalyst was prepared by direct pyrolysis of the mixture of PCPAT,iron(II)acetate and zinc chloride.The as-obtained Fe-N/C catalyst possessed a very high specific surface area of 1739 m2 g-1 and a very high total pore volume of 1.53 cm3 g-1.XPS analysis indicated that the N content of Fe-N/C catalyst was found to be 1.7 at%.The catalytic activities of Fe-N/C catalyst prepared under optimal conditions towards ORR were investigated.It was found that the Fe-N/C catalyst exhibited excellent ORR activity in alkaline electrolytes with a high onset potential of 0.023 V(vs.Ag/Ag Cl),a half-wave potential of-0.084 V(vs.Ag/Ag Cl),and a large limiting current density of 6.3 m A cm-2 together with excellent methanol tolerance and durability.(2)Preparation and ORR electrocatalytic performance of NC catalyst based on PCPAPT.Organic porous polymer,PCPAPT,was also prepared by the trimerization reaction of 2,4-di(p-cyanophenylamino)-6-(p-pyridylamino)-1,3,5-triazine(CPAPT)using anhydrous Zn Cl2 as the catalyst.Then the NC catalyst was prepared by the direct pyrolysis of PCPAPT at high temperature.The catalytic activity of NC catalyst towards ORR was also systematically investigated.The obtained NC-1000 catalyst exhibits superior ORR activity in alkaline electrolytes with a high onset potential of-0.005 V(vs.Ag/Ag Cl),a half-wave potential of-0.120 V(vs.Ag/Ag Cl),and a large limiting current density of 5.77 m A cm-2as well as excellent methanol tolerance and durability.