Preparation And Investigation Of Based On N-Doped Carbon Materials Electrocatalysts For Oxygen Reduction Reaction

Increasing demands of energy have stimulated intense research on new energy conversion and storage systems with high efficiency,low cost and environmental benignity.Oxygen reduction reaction(ORR)is of great significance for clean and efficient energy conversion devices such as fuel cells and metal-air batteries.But,it has been a great challenge to develop efficient,stable and low-cost electrocatalysts for the oxygen reduction reaction(ORR).Although platinum-based material can meet the require-ment of high ORR activity,the high cost and scarcity of platinum limit their practical applications.Therefore,many non-precious catalysts have been designed,mainly including metal-free heteroatoms doped carbon materials,M-N-C catalysts.This paper mainly focus the M-N-C catalysts and heteroatoms doped carbon materials catalysts to carry out the following works:(1)Here the hybrids of CoFe layered double hydroxides(CoFe-LDHs)with polydopamine spheres(PDAs)were prepared by growing Co Fe-LDHs at the surface of PDAs in situ and their catalytic activity toward the ORR was investigated in detail.The results show that the as-prepared CoFe-LDHs/PDAs hybrids exhibited higher ORR catalytic activity with 4e-route selectivity than pure CoFe-LDHs,PDAsand even calcinated CoFe-LDHs/PDAs,which displays synergistic effect between CoFe-LDHs and PDAs for ORR.Moreover,the CoFe-LDHs/PDAs hybrids demonstrated better durability than commercial Pt/C ORR catalysts.To uncover the ORR mechanism,the interaction between CoFe-LDHs and PDAs were characterized by XPS and the ORR activity of Co Fe-LDHs/PDAs and CoFe-LDHs/PDAs leached with acid was compared.The catalytic behavior of CoFe-LDHs/PDAs hybrids is consistent with a dual-site ORR mechanism.(2)We use a simple experiment method to synthetic Co-N-C catalyst by heat treatment.For Co-N-C catalyst system,chitosan play the role of N and C resources,and EDTA play of chelating agent to chelating cobalt.Especially,we found that chitosan could not form carbon spheres without EDTA.The Co-N-C catalyst exhibited high electrocatalytic activity and durability for the oxygen reduction reaction(ORR)with 4e-route selectivity.(3)An intumescent flame retardant(IFR),including melamine(MA),ammonium polyphosphate(APP),and polydopamine(PDA),was utilized as the precursor to prepare P,N co-doped hierarchically porous carbon which exhibited high electrocatalytic activity and durability for the oxygen reduction reaction(ORR).This finding indicates that an ingenious design of the precursor can lead to functional carbon materials using a simple process.