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The Preparation Of Hetero-element-doped Carbon-based Catalysts And Their Oxygen Reduction Performance

Posted on:2020-01-12Degree:MasterType:Thesis
Country:ChinaCandidate:J LiuFull Text:PDF
GTID:2431330578461855Subject:Engineering
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Carbon-based nanomaterials have the advantages of high temperature resistance,chemical resistance,and low cost,and play an important role in many fields such as energy conversion devices.Among them,the biomass-based carbon material has been widely used by researchers in recent years because of its sustainable circulation,wide source,clean and pollution-free.In order to develop a cheap and efficient new heteroatom-doped carbon material,this paper has carried out a series of studies based on the unique molecular structure and three-dimensional network structure of bacterial cellulose,using it as a carbon source for structural regulation and design synthesis route.Work as follows:(1)Based on bacterial cellulose,methylene blue as nitrogen source and sulfur source,ammonium persulfate as oxidation inducer,in-situ polymerization of methylene blue on cellulose,carbonization after 800? high temperature,three-dimensional network nitrogen,sulfur-doped carbon nanomaterials.The shape is regular,with multi-stage pore structure and high specific surface area(729 m2/g).The physical characterization confirmed that the nitrogen element and the sulfur element were successfully uniformly incorporated into the skeleton of the carbon cellulose,and the doping amounts were 3.2%and 0.8%,respectively.The electrochemical performance characterization showed that the material had excellent oxygen reduction catalytic activity in 0.1 M KOH electrolyte,and the half-wave potential was similar to that of 20%commercial platinum carbon(Pt/C).At the same time,its stability and methanol resistance are superior to commercial Pt/C.(2)Exploring the preparation method of iron,nitrogen and sulfur co-doped carbon materials.Combined with the advantages of in-situ polymerization and metal coordination,dopamine is used as a carbon source,and ammonium peroxydisulfate is used to initiate dopamine radical polymerization on the surface of bacterial cellulose.Ferric chloride hexahydrate is a metal iron source,which is coordinated with polydopamine.The effect is to introduce Fe3+ onto the surface of the bacterial cellulose,and to obtain the target material by carbonization and acid treatment.The material is a composite of N,S-doped carbon and y-FeOOH,and has a lamellar structure with a specific surface area of 774.5m2/g.In an alkaline environment,it shows excellent oxygen reduction catalytic activity.The oxygen reduction half-wave potential(0.83 V)is better than 20%commercial Pt/C(0.82 V)10mV,and it also has better resistance than Pt/C.Methanol and stability.According to the analysis,the excellent oxygen reduction performance is attributed to the synergistic effect of a large number of y-FeOOH active sites with nitrogen and sulfur.In addition,it is coated on a positive carbon cloth of a zinc-air battery to obtain a high discharge power density(?92 mW cm-2)and a specific volume ratio(734 mA h g-1),exceeding the commercial Pt/C(?78mW cm-2,720 mA h g-1).It indicates that the catalyst can improve the conversion efficiency of chemical energy conversion of zinc-air battery into electric energy.This study provides technical support and theoretical basis for the development of new carbon-based oxygen reduction catalysts.
Keywords/Search Tags:Bacterial cellulose, arbon nanomaterials, electrocatalyst, heteroatom doping, oxygen reduction reaction, zinc air battery
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