Preparation Of Self-doped Nitrogen Porous Carbon And Effect Of Redox Additives On Its Electrochemical Properties

Metal Organic Framework?MOFs?are network-like skeleton compounds formed by the connection of transition metals with organic ligands containing oxygen or nitrogen.MOFs as precursors are used has broad application prospects in the field of material synthesis because its highly controllable composition structure and highly ordered porous structuren.In this paper,the key problem of low energy density of supercapacitors is studied.MOFs derived self-doped porous carbon is prepared by one step carbonization using MOFs as precursor.The effects of structure of MOFs derived self-doped porous carbon and nitrogen atom doping on electrochemical properties are investigated.In addition,redox materials are added to the derived self-doped porous carbon and alkaline electrolyte that the mechanism of enhancing the electrochemical performance of supercapacitors was described.The implementation of this project is expected to improve the energy density while maintaining the advantages of supercapacitors.The preparation of functional carbon materials based on MOFs and their research application in supercapacitors provide experimental basis.The research work of this paper mainly includes the following aspects:?1??H₃O?_0.5[Zn?1,2,4,5-BTBC?_0.25?ATZ?_1.5]·x?solvent?_n,?denoted as:ZAB?was synthesized by hydrothermal method and self-doped nitrogen porous carbon ZABC-T was derived from ZAB by one-step carbonization.The self-doped nitrogen porous carbon ZABC-800 with honeycomb structure,high specific surface area of 1008 m² g^-11 and high nitrogen content 4.09%.In three-electrode system,the ZABC-800 shows an excellent specific capacitance of 316.3 F g^-11 at 1.0 A g^-11 and remarkable cycling stability?81.9%retention after 5000 cycles?.?2?The self-doped nitrogen porous carbon ZPDC-T with excellent supercapacitor performance were successfully prepared by using Zn₄?PDC?₄?DMF?₂·3DMF?denoted as:ZPD?as nitrogen-rich precursor by one step carbonization method.The self-doped nitrogen porous carbon ZPDC-850 with disordered porous structure,high specific surface area of1520 m² g^-11 and high nitrogen content 6.47%.In three-electrode system,The unique pore structure and nitrogen functionalities enable the self-doped nitrogen porous ZPDC-850 to exhibit a electrochemical properties of 265.1 F g^-11 at 1.0 Ag^-11 in 6 M KOH electrolyte,which is attributed to the contributions of double layer capacitance and pseudocapacitance,with good cycle stability?79.2%retention after 5000 cycles?.Self-doped porous carbon ZPDC-850 has excellent electrochemical performance and good cycle stability.?3?Self-doped nitrogen porous carbon ZYC-T with excellent supercapacitor performance were successfully prepared by using Zn₂?ATRZ?₂SO₄·3H₂O?denoted as:ZY?as the precursor by one-step carbonization method.Self-doped nitrogen porous carbon ZYC-800 has the largest specific surface area of 725 m²g^-11 and nitrogen content of 7.26%.In three-electrode system,ZYC-800 has highest specific capacitance of 205.5 F g^-11 at a current density of 1.0 A g^-11 in 6 M KOH electrolyte.Diphenylcarbazide of different mass?ZYC-800-W?was introduced into self-doped nitrogen porous carbon ZYC-800.The ZYC-800-5.3 as electrode exhibits a maximum specific capacitance of 274.1 F g^-11 at current densities of 1.0 A g^-11 in 6 M KOH electrolyte.Energy density is 1.33 times higher than that of the original one without diphenylcarbazide.After 5000 cycles of constant current charging and discharging,the capacitance retention rates of self-doped nitrogen porous carbon ZYC-800 and ZYC-800-5.3 were 71.1%and 72.8%,respectively.The results show that the self-doped nitrogen porous carbon ZYC-800 has excellent electrochemical performance and good cycle stability.The addition of diphenylcarbazide has a great contribution to improving the electrochemical performance.?4?A porous carbon?denoted as ABIC-T?derived from{[Ag₃?BTC??IM?]·H₂O}_n,?denoted as ABI?has been synthesized by one-step carbonization method,the porous carbon material?denoted as ABIC-750?displayed a high specific capacitance of142.2 F g^-11 at 1.0 A g^-11 and good electrochemical performance in the three electrode system.porous carbon ABIC-750 has the largest specific surface area of 602 m²g^-1.The porous ABIC-750 showed a better rate and higher specific capacitance In order to improve the electrochemical performance of supercapacitors,Alizarin sulfonate sodium were added to6MKOH as mixed electrolyte?denoted as ASS-n?.It presented maximum specific capacitance of 817.1 F g^-11 for porous carbon ABIC-750 in ASS-4 mix electrolyte at a current density of 1.0 A g^-1,the energy density in ASS-4 is 5.75 times that in 6M KOH.After 5000 charges and discharges,the capacitance retention rates of porous carbon ABIC-750 in 6 M KOH and ASS-4 were 91.05%and 71.05%,respectively.It shows that the addition of Alizarin sodium sulfonate can improve the telephone performance of supercapacitor and it is a simple and effective way to improve the specific capacitance.