Preparation Of Nitrogen-doped Porous Carbon And Their Electrochemical Properties

In recent years,the research of supercapacitors has developed rapidly.The electrode material is the core component of the supercapacitor.Carbon materials as an ideal electrode material has high capacitance,high specific surface area and high conductivity.Moreover,the preparation process is simple and cheap.Carbon materials doped with nitrogen-containing functional groups can greatly improve the conductivity of carbon materials,optimize the pore size distribution of materials and improve the wetting of the surface of the material.In addition,N-doped carbon materials can produce pseudocapacitance behavior so that it can increase the specific capacitance of the carbon materials.In this paper,sucrose and glucose were used as raw materials to fabricate carbon materials.The nitrogen-containing functional groups and graphene were successfully introduced into carbon materials through the hydrothermal and combustion processes.Finally,some supercapacitor electrode material with promising application was fabricated successfully.1?In this paper,the improved Hummers method was used for fabricating GO.Its morphology and structure were characterized by a series of test methods.GO as a strong conductive component was introduced into the carbon microspheres,thereby increasing the specific capacitance of the carbon microspheres.2 ? The carbon microspheres were fabricated by one step hydrothermal method using glucose solution as carbon source.It was found that the diameter of the carbon microspheres increased by 15 times in the diameter and the pyridine?N-6?and pyrrole /pyridone?N-5?Nitrogen were successfully introduced into carbon microspheres after adding g-C₃N₄ quantum dots.In this paper,we studied the changes of the microspheres doped with graphene and the influence of graphene on the electrochemical properties.By comparison,the electrochemical performance of AC-3 is relatively good and its specific capacitance is 150Fg^-1 in 2Ag^-1.Its capacitance is 1.3 times higher than AC-2which only doped with g-C₃N₄ quantum dots.Its specific capacitance is 8.6 times higher than AC^-1 which is fabricated by glucose solution.The AC impedance test?EIS?demonstrates that the resistance of the carbon microspheres doped with graphene decreases.It is indicated that the graphene can enhance the conductivity of the carbon microspheres.3 ? N-doped carbon was fabricated by one-step combustion synthesis using melamine as nitrogen source,sucrose as carbon source and NaHCO₃ as blowing agent.Then,activated porous carbon?PC?was successfully fabricated through heat treatment in an inert gas.In this paper,the effects of melamine,NaHCO₃ and different heat treatment temperature on the electrochemical properties of porous carbon were studied.It was found that melamine mainly introduced nitrogen-containing functional groups for porous carbon.NaHCO₃ is mainly used as activator to optimize the pore size distribution of the material.The specific surface area of porous carbon may reach 2084.9 m2g^-1.The BET analysis shows that the material is a typical microporous material with a small number of mesopores.Electrochemical tests show that the porous carbon has a good cycle reversibility,better electric double layer capacitance behavior,better charge and discharge efficiency and smaller impedance.At a current density of 1A/g,the specific capacitance of the PC-700 can reach 185Fg^-1.