Preparation And Applications Of Noble Metal-free Carbon-based Catalysts Via Self-assembly Strategy

Noble metal-free nitrogen-doped carbon(M-N/C)is a kind of carbon nanomaterial that doped with non-noble metal element M(e.g.Fe,Co,and Cu)and N element.It has been widely used as a substitution of Pt in electrocatalysis and energy conversion owing to its excelent electrocatalysis performance,high specific surface area and stable structures.Doping can not only retain some characteristics of the carbon nanomaterial,but also can improve the catalytic performance of the nanocarbon material through modulating the electronic and chemical structures of M and N,which can be easily achieved by tuning the structure of the precursor/ligand.The self-assembly strategy is the most widely used method for preparing controllable precursors,such as metal-N coordination,intermolecular hydrogen bonding,conjugation,and covalent coordination,providing possibilities for various assemble ways.For example,by selecting different ligands,the pores and properties of metal-organic frameworks(MOFs)/covalent organic frameworks(COFs)can be controlled.However,the study of the general relationship between assembly strutures of precursors and properties of as-prepared M-N/C remains largely unexplored.In this thesis through the regulation of the structure and crystal inity of the precursors,the structures-properties of the noble metal-free N-doped carbon material were studied.This thesis mainly includes the following two sections:1.By a supermolecular self-assembly driven strategy,we prepared aggregates with a certain micro-nanostructure.Different precursors with different crystal inity were formed by using different solvents to adjust the strength of hydrogen bonds,and then the pyrolysis was undertaken at high temperature in nitrogen protection conditions.The relationship between different crystal ine precursors and N-doped carbon materials was studied.The similar way was also extended to the synthesis of Fe,N doped carbon materials.The as-prepared catalysts were also finally applied to Zn-air batteries with competitive performances.2.In order to improve the kinetics of the high temperature solid-state reaction,the gas-has phase is introduced alternatively in the solid phase reaction.Similar to traditional chemical vapor deposition(CVD)method in production of carbon nanotubes,diacyadiamide was used to generate gas source,menwhile Co oxide/chloride and CoN/C composites were used as catalysts.In the crucible,the multi-walled Co,N codoped carbontubes were obtained,which showed a high performance comparable to commercial Pt under acidic or alkaline conditions,and the as-prepared catalysts were also finally applied to the oxidation of quinone/pentahy droxymethyl furfural.