Preparation And Electrochemical Properties Of Carbon Materials Derived From Oxygen Bridging Porous Organic Polymers

Porous carbon materials have been widely used in the field of energy storage and conversion due to their advantages of high conductivity,diverse structure,enhanced stability and low cost.Among them,three-dimensional（3D）porous carbon has been a research hotspot in the field of new energy because of its advantages of interpenetrating pore structure,high electrical conductivity and good structural stability.In this paper,a series of high performance supercapacitors（SCs）electrode materials with 3D structure and oxygen reaction electrocatalysts which can be used for rechargeable zinc-air batterys（ZABs）were prepared by high temperature pyrolysis using a novel oxygen-bridged porous organic polymer（OPOP）as precursor.Based on the chemical composition,morphology and electrochemical properties of carbon materials,the electrochemical reaction mechanism and the factors influencing the activity of carbon materials were analyzed and studied.The following is the main research work:（1）Preparation and application of O/N codoped porous carbon derived from hydroquinone organic framework.OPOP₂ was synthesized by polycondensation with hydroquinone and melamine chloride as monomers.The 3D graded porous carbon（OPOP₂-800）derived from oxygen-bridged organic polymers was prepared by high temperature pyrolysis using the polymer as a precursor,Na Cl as a by-product generated in situ as a molten salt template and Na₂CO₃ as an activator.OPOP₂-800 has an interconnected 3D porous structure,a high specific surface area(SSA,2239.5 m² g^-1)and a high O/N doping content（7.88 at.%O and 6.37 at.%N）,OPOP₂-800 shows a excellent specific capacitance(347 F g^-1@0.5 A g^-1)in the three-electrode system（6M KOH）.OPOP₂-800 showed high electrochemical performance and excellent cyclic stability in neutral and alkaline electrolytes in the two-electrode system.In addition,the charge storage mechanism of OPOP₂-C was revealed by DFT calculation.（2）Preparation and application of Fe/Ni co-doped porous carbon derived from phloroglucinol organic framework.OPOP₃ was synthesized by polycondensation reaction with p-phenylgallol and melamine chloride as monomers.Then,using the bimetal coordination polymer obtained by the coordination of the polymer with Fe³⁺/Ni²⁺as the precursor,Na Cl that the by-product generated in situ during polycondensation reaction as the salt template,FeNi/N-C with 3D hierarchical porous structure was prepared by high temperature pyrolysis.FeNi/N-C was found to have an interpenetrating network structure and a large specific surface area(218.67 m² g^-1).FeNi/N-C prepared under the optimal conditions shows excellent dual-function ORR/OER catalytic activity and cycling stability and its potential differenceΔE（0.755V）is close to Pt/Ir composite catalyst.The assembled secondary ZABs have higher power density(111 m W cm^-2),higher specific capacity(855 m Ah g_Zn^-1@5 m A cm^-2)and excellent charge-discharge performance and cycle stability.In addition,DFT calculation revealed the reason for the excellent bifunctional catalytic activity of FeNi/N-C.