Preparation Of PANI/graphene-based M-N/PGO Catalysts And Their Performance For Electrecatalytic Oxygen Reduction

Design and preparation of inexpensive catalysts with high performance for oxygen reduction reaction has become the most efficient way to accelerate the commercial development of DMFC.M-C-N composites have been considered as the potential substitute for noble metal catalysts.However,the common carbon supports such as graphene and carbon black used in M-N-C catalysts have the problem of easy agglomeration,which is not conducive to the formation of engineering beneficial morphology and structure of the catalysts.Based on the above analysis,this thesis presents a simple method to construct high-performance M-N/PGO catalysts by using the para-phenylenediamine functionalized GO?PGO?as the carbon support.Furthermore,the effect of catalysts'morphology and structure on its electrocatalytic performance was explored,providing the experimental basis for the design of catalysts.?1?The optimal morphology and structure of Fe?Co?-PANI/PGO catalysts,which prepared by PGO,PANI and various metals?Fe or Co?,are explored for the ORR activity.The PGO not only solve the problem of agglomeration of the graphene sheets,but also increase the N content in the carbon support,which is beneficial to the increase of active site density.The optimized Fe-PANI/PGO exhibited good electrocatalytic performance with onset potential of 0.939 V?vs.RHE?,half-wave potential of 0.871 V?vs.RHE?and electron transfer numbers of 3.62,respectively.Meanwhile,the half-wave potential of Fe-PANI/PGO,after 10,000 cycles of CV scanning,only decreases by 6 mV,which indicates that the Fe-PANI/PGO has a good stability.?2?Through combining different nitrogen/carbon precursors,including polyaniline?PANI?,dicyandiamide?DCDA?and PGO,the best performing Fe-PD/PGO catalyst derived from PANI+DCDA was prepared successfully.The combination of PANI+DCDA likely further increase the content of doping nitrogen atom,which is able to increase the number of active sites.Electrochemical tests show that Fe-PD/PGO possesses a positive half-wave potential of 0.886 V?vs.RHE?and electron transfer numbers of 3.98.In addition,the stability of Fe-PD/PGO is also excellent with only decreasing 7 mV of half-wave potential after 10,000 cycles of CV scanning.?3?The FC-PD/PGO was prepared by simple heat-treatment using FeCl₃·6H₂O and Co?NO₃?₂·6H₂O as bimetallic sources,PANI and DCDA as double nitrogen sources,and PGO as the carbon support.The possible synergistic effect between Fe and Co likely further increases the graphitization degree of catalyst,which is beneficial to improve the conductivity of the catalyst and N-P/N-G.As a result,the FC-PD/PGO exhibited outstanding electrocatalytic performance with onset potential of 0.955 V?vs.RHE?and half-wave potential of 0.864 V?vs.RHE?,respectively.The most important is that the current density is improved dramatically to 5.75 mA·cm^-2 at 0.200 V?vs.RHE?.Meanwhile,the FC-PD/PGO possesses the enhanced stability with only decreasing 6 mV of half-wave potential after 10,000 cycles of CV scanning.