Design,Preparation And Property Of Porous Carbon Materials

Owing to their high specific surface area,acid and basic resisting,controllable pore size and structure,easy modification of surface and excellent electronic conductivity,porous carbon materials have exhibited great potential applications in the fields of lithium-ion batteries?LIBs?,supercapacitors,catalyst and gas storage,and at the same time they also become the focus of many researchers.It is found that the specific surface area,the pore structure,the microstructure and the the heteroatom doping have great influence on the properties of the porous carbons.At present,the synthesis of porous carbon materials are still suffering from some problems,such as high cost,low yield,complex preparation process and pollution,which have seriously hindered their wide applications.Therefore,we mainly focus on developing different synthesis methods by controlling the synthesis conditions to obtain low-cost porous carbons with high specific surface area and controable microstructure for meeting the needs of applications.In this thesis,we have successfully synthesized a series of porous carbon materials with special morphology and structure,by using soft-template self-assembly method,oxidative template assembly method,hydrothermal assisted synthesis method and KOH activation,with phenolic resin,polypyrrole,polyaniline and biomass materials as carbon sources.Meanwhile,we also studied their performances in CO₂ capture and separation,LIBs,supercapacitors,and catalytic reaction.1.The polymer precursor with micro-flower structure has been prepared by a soft-template assisted self-assembly method using phenolic resin as a carbon source,F127as a soft template and the hydrazine hydrate as a structure-directing agent?also as a nitrogen source?.After carbonization and further KOH activation,a series of N-doped hierarchically porous carbons with high specific surface area and flower-like micro-structure are obtained.When used as the anode materials for LIBs and as adsorbents for the CO₂ capture and separation,these porous carbons exhibit excellent performance.The sample A-NCF-4 with high surface area of 2309 m² g^-1,total pore volume of 1.03 m³g^-1 and microspore size below 1 nm,exhibits a stable reversible capacity of 807 mAh g^-1 at the current density of 0.3 A g^-1,and high CO₂ adsorption capacities of 6.52 mmol g^-1 at 1bar and 19.42 mmol g^-1 20 bar,under 0?.The selectivity of CO₂/N₂ is 10.95,which is calculated from the ratio of the initial slopes of CO₂ and N₂ adsorption isotherms.2.With environment-friendly pyrrole monomer as carbon source,the polypyrrole precursor with nanofiber network structure has been prepared by an oxidation template assembly method at 0-3?.After one-pot carbonization and KOH activation process,a series of porous carbon nanofiber webs with high specific surface area are synthesized.These carbon materials exhibit excellent CO₂ capture performance and catalytic performance.Especially,sample CNFWs-600-2 exhibits high CO₂ capture capacities of6.44 mmol g^-1 and 4.42 mmol g^-1at 0? and 25?,respectively,under 1 bar,and it also exhibits a good selectivity for CO₂/N₂ separation.Furthermore,the CNFWs-600-2 is also found to be an efficient catalyst towards the cycloaddition of CO₂ with epibromohydrin and epichlorohydrin to synthesize bromopropene carbonate and chloropropene carbonate,with the yields of 95%and 86%,respectively.3.With the low-cost aniline as the carbon source,polyaniline nanofibers are synthesized though an oxidation template assembly method under ice bath?0-3??condition.Via thermal annealing,carbonization and further KOH activation processes,a series of N-doped hierarchically porous carbon nanofibers are prepared.The as-obtained carbon materials have unique hierarchical cross-linking porous structure,which is convenient for CO₂ and lithium ion transportation and storage.The sample CNFs-2 exhibits high CO₂ capture capacities of 5.68 mmol g^-1 and 4.01 mmol g^-1 under 1 bar,at 0? and 25?,respectively.The selectivity of CO₂ over N₂ for CNFs-2 is calculated from binary mixture of(V?N₂?:V?CO₂?=85:15 according to ideal adsorbed solution theory?IAST?.Sample CNFs-4 exhibits stable reversible capacity of 1445 m Ah g^-1 at the current density of 100 m A g^-1 after 100cycles as an anode for LIBs.4.The wastes of mangosteen peels are successfully converted into carbon materials with high surface area and three dimensional porous structure though a simple and controllable hydrothermal pre-treatment in alkaline solution followed by a further carbonization process.These carbons as CO₂ adsorbents and electrode materials exhibit excellent adsorption capacitiesanddesirablesupercapacitorperformances.Especially,sample3D-HP-CFW-11-18 exhibits CO₂ adsorption capacity as high as 6.93 mmol g^-1 at 0? and1 bar,and shows excellent capacitive performance with a specific capacitance of 240 F g^-1at the current density of 1 A g^-1 in three electrode system of 6 M KOH.This experiment provides an effective reference for the preparation of porous carbon materials from biomass materials.