Preparation And Electrochemical From Properties Of Fe-N-C Material Derived Amino Acid

Functional carbon materials are used in the filed of energy and catalyst due to their excellent physical and chemical properties such as good conductivity,large specific surface area,and diverse structures.Functional carbon materials are widely used as a crucial electrode material because of their excellent physical and chemical properties in energy conversion and storage.It is of great significance to develop new functional carbon materials and explore their application in the storage and conversion of renewable energy.In recent years,it has attracted extensive attention and has become a study hotspot to prepare Fe-N-C materials with hierarchical porous structures and rich active sites such as Fe and N by using various types of iron,nitrogen and carbon sources,and apply them as electrode materials to the field of energy storage and conversion.Amino acids are a kind of green compounds,which have unique amphoteric properties because they contain both amino and carboxyl functional groups.They are often used as morphology assistants and functionalizing agents when preparing functional nanomaterials.In this study,ferric chloride is used as the iron salt,and amino acid and biomass of containing rich amino acid are used as the sources of carbon and heteroatoms to make a series of Fe-N-C materials and their electrochemical performances are investigated.The main contents are as follows:（1）Fe-N-C materials were prepared by one-step carbonization with leucine as the carbon and nitrogen source,ferric chloride as the activator and iron source.The effect of carbonization temperature on the composition,structure and final electrochemical performance of the materials was studied.The results show that the as-prepared sample Fe-N-C has a sheet-like morphology,large specific surface area(1410 m² g^-1)and Fe mainly exists in the form of Fe₃C and Fe₂O₃ particles and Fe-N₄active sites,and N-doping forms mainly are graphitized nitrogen.As ORR electrocatalyst,the sample has a high initial potential(E_onset=0.90 V)and half-wave potential(E_1/2=0.82 V),a nearly 4e^-reaction pathway,a Tafel slope close to commercial Pt/C,and has better methanol resistance and cycle stability performance than that of Pt/C.In addition,the sample also has excellent capacitance performance:the specific capacitance is 240 F g^-1 in an alkaline electrolyte under a current density of 0.5 A g^-1,the rate performance is also good.In a symmetric symmetric two-electrode system,it has a high energy density of 15.4 Wh kg^-1 at a power density of 225 W kg^-1in neutral electrolyte,and also exhibits excellent cycle stability in alkaline electrolyte.（2）Compared with single doping,double doping can further enhance the ORR catalytic performance of the material.So,in this part,the Fe-based N,S co-doped carbon material is prepared by one-step high-temperature pyrolyzing using cysteine as the source of carbon,nitrogen and sulfur,and ferric chloride as the source of activator and iron.The effect of carbonization temperature on material composition,structure and final electrochemical performance was studied.The results show that the material has a loose and porous sheet structure with a large specific surface area(1203 m² g^-1).As an ORR electrocatalyst,the material has a high initial potential（0.92 V）and limit-current density(5.12 m A cm^-2),and has nearly 4 electric reaction paths,a Tafel slope close to commercial Pt/C,and has better methanol resistance performance than Pt/C.（3）N,S co-doped porous carbon was prepared by using rice lees with rich amino acids as the carbon and heteroatom source,and ferric chloride as the activator and catalyst.The electrocatalytic performance of materials at different temperatures were explored.The study found that the obtained material had a higher degree of graphitization and contained N and S heteroatoms with a larger specific surface area(1357 m² g^-1).Oxygen reduction performance tests show that the material exhibits a relatively positive initial potential（0.83 V）,nearly four electron paths,better methanol resistance and cycle stability performance than Pt/C in alkaline electrolytes.