Multifunctional Catalytic Performance Of Multicomponent Doped Suger-coated Haws Stick-like Nanofibers

Zinc-air battery has characteristics of high energy density,high conversion and environmental friendliness,but its large-scale application is restricted by precious metal catalysts for cathode.Many kinds of organic pollutants in water are difficult to degrade,which greatly endangers people's health.Therefore,it is important to study environmentally-friendly and low-cost multi-functional catalysts that can be used for Zinc-air batteries and organic matter degradation.Recently,heteroatoms and transition metals doped carbon materials with large surface have received great attention as multifunctional catalysts.In this paper,1D nanofibers are combined with porous MOF materials to introduce transition metals and heteroatoms as multifunctional catalyst precursors.The main research contents and results are as follows:(1)Coating ZIF-67 nanocrystals on the surface of PAN nanofibers by high voltage electrospinning and ZIF-67 in situ growth technique to form sugar-coated haws stick-like nanofibers and then carbonized to obtain Fe/Co-N/P-T(T stands for tempreture).Fe/Co-N/P-T exhibits different morphology,and Fe/Co-N/P-9 can maintain the sugar-coated haws stick-like structure.The metal exists in the form of Fe5C2 and Co2P nanocrystals,and the surface is coated with graphite carbon layer to be embedded in the porous carbon structure.Fe/Co-N/P-9 has a graded porous structure and the highest content of pyridine-N and graphite-N.(2)Fe/Co-N/P-9 exhibites ORR catalytic activity compared to that of Pt/C in an alkaline environment with an onset potential of 0.96 V,and a halfwave potential of 0.85 V,and higher catalytic stability and methanol resistance.In addition,Fe/Co-N/P-9 also exhibites OER catalytic performance close to commercial RuO2(E10 mAcm-2=1.66 V).The open circuit voltage of a Zinc-air battery assembled with Fe/Co-N/P-9 as catalyst is 1.389 V,the specific discharge capacity is 565 mAh g-1Zn and the energy density is 683.80 Wh·kg-1Zn under current of 5 mA cm-2,higher than that of Pt/C+RuO2,and the number of constant current charge and discharge cycles reaches 139 times.(3)The Fe and Co contained in Fe/Co-N/P-9 are common sulfate radical activating substances,?-electrons in highly graphitized carbon network can also activate sulfate radicals and the introduction of heteroatoms in carbon materials can modify the electronic structure of adjacent carbon,activating?-electrons and improving electron transport capability.Fe/Co-N/P-9 can activate potassium persulfate to produce sulfate radicals to achieve complete degradation of RhB within 35 min.Both sulfate radicals and hydroxyl radicals exist in the system.Temperature,pH,concentration,dye structure,anion and cation and humic acid have important effects on dye degradation,and its reusability needs to be improved.