Preparation And Application Of Nitrogen-Doped Porous Carbon Oxygen Catalyst Derived By Hard Template

With the increasing demand for renewable energy,new energy storage devices(such as fuel cell and metal-air battery)should be commercialized further.However,limited by the complex oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),the current noble metal catalysts for those reactions account for half of the manufacturing cost,which is essential for the development of low-cost and high-performance oxygen electrode catalysts.Recently,porous carbon materials have attracted lots of attention due to their excellent electrical conductivity and high specific surface area.Meanwhile,nitrogen-doped and hard template strategy can effectively improve the catalytic performance of the materials.In this paper,we explored the preparation of nitrogen-doped porous carbon materials drived by hard template,which were applied in high efficiency ORR catalysis and Zn-air battery respectively,providing new ideas for the preparation of oxygen electrode catalysts.In the first part,the nitrogen doped porous carbon(NPC)was prepared by hard template method.The ORR performance can be comparable to 20%Pt/C(the half wave potential is 0.85 V).In addition,the high BET specific surface area(2511 m2.g-1)increases the number of superficial C-N active sites.And the mass transfer process is greatly optimized.In this work,a low-cost method for preparing metal-free oxygen reduction catalyst was proposed,which is a kind of effective interfacial control strategy.In the second part,the bifunctional oxygen electrode catalyst was constructed by assembling distinct active moieties into one composite(PA-CoFe@NPC).The N-doped porous carbon(NPC)drived by hard template contains abundant C-N active sites to provide excellent ORR performance(the half wave potential is 0.85 V).While the OER active sites(CoFe-OOH)generated in situ during high potential of OER process,which provided excellent OER performance(the overpotential is only 384 mV when OER current density reaches 10 mA·cm-2),that is better than IrO2.PA-CoFe@NPC based Zn-air battery shows a better charge-discharge performance than 20%Pt/C+IrO2.In addition,the maximum power density of the battery is up to 156.3 mW·cm-2,and the battery can operate stably for 170 hours.In this work,a new strategy for construction of bifunctional oxygen electrocatalyst for rechargeable Zn-air battery is proposed.In other words,distinct active sites can be assembled into one composite material,and different electrocatalytic reactions are catalyzed at distinct active sites,which offers a fresh perspective to develop bifunctional oxygen electrode catalyst.