Controllable Construction Of Polymer Precursor Based On Kabachnik-Fields Reaction And Preparation Of Doped Carbon Materials

As a typical energy device,supercapacitor has attracted tremendous attention due to its features of rapid charge-discharge rate,long cycle life,superior power density.The electrode materials play a vital role in determining the performance of a supercapacitor device.Benefiting from the rapid development of materials science,researchers have exploited numerous supercapacitor electrode materials.Carbon materials and their composites have been widely used as electrode materials for supercapacitors.Polymeric precursor design has become a widely adopted strategy to create high performance carbon materials,as it can not only introduce heteroatoms into the carbon matrix,but also have a high capability to adjust the pore nature of the carbon materials.In addition,there are multiple functional groups in the polymer network,which can form hydrogen bonds,coordination,and electrostatic interactions with inorganic particles to induce polymers onto the surface of inorganic particles,thereby forming a core-shell structure.Based on this,utilizing Kabachnik-Fields reaction among aldehyde,amino with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO),selective etching method based on the molecular exchange reaction of dynamic imine bond and hydrogen bonding between amino and inorganic nanoparticles,we prepared polymer nanospheres containing N and P elements and iron oxide@polymer core-shell particles.After a simple calcination treatment,N,P codoped carbon spheres(PCNPs)and iron oxide/iron@carbon(Fe2O3/Fe@CNP)coreshell particles were obtained and their applications in supercapacitors were investigated.The main research work are as follows:(1)Three kinds of porous polymer nanospheres were prepared by selecting different amino and aldehyde-based molecular building blocks,relying on the Kabachnik-Fields reaction of amino,aldehyde and DOPO,and the dynamic exchange reaction of imine bonds,this method is universal to various amino and aldehyde monomers.For example,porous polymer nanospheres(PIDPs)were prepared using 1,3,5-tri(4-aminophenyl)benzene(TAB),terephthalaldehyde(TPAL)and DOPO as raw materials.PIDPs were directly pyrolyzed to obtain N and P co-doped porous carbon nanospheres(PCNPs).The effects of aniline concentration on the morphology and structure,heteroatom content and pore structure of PCNPs,and the influence of these factors on the supercapacitor performance were studied.Three-electrode tests showed that PCNP2 had a specific capacitance of up to 359.5 F g-1 at 0.5 A g-1 under an acidic condition(1 M H2SO4)and a high specific capacitance of 224.0 F g-1 at 20 A g-1.The cycle stability of PCNP2 was also excellent,and the capacitance retention rate after 5000 cycles was 95%.Using PCNP2 as electrodes and H2SO4/PVA as gel electrolyte to assemble semisolid-state supercapacitors,the test results showed that the specific capacitance was up to 226.7 F g-1 at 0.2 A g-1 and 126.0 F g-1 at and 20 A g-1.(2)Utilizing the hydrogen bonding between amino and inorganic nanoparticles,the Kabachnik-Fields reaction of the three monomers(TAB,TPAL and DOPO)was restricted to the surface of the inorganic nanoparticles,and a series of inorganic@polymer core-shell nanoparticles were prepared,which proved that the coating method had high adaptability.Fe2O3@IDP3 was used as the precursor and subjected to high-temperature calcination,and Fe2O3/Fe@CNP core-shell composites were prepared.The morphology,heteroatom content and pore structure of the composites were characterized,then the influence of these factors on Faradaic capacitance was investigated.The electrochemical results showed that the Fe2O3/Fe@CNP core-shell composite had a specific capacitance of 244.0 F g-1 at a current density of 0.5 A g-1 under alkaline conditions(1 M KOH).