Preparation And Performance Of N Doped And N/S Codoped Biomass Based Carbon Materials

Due to depletion of fossil fuels,biomass has attracted enormous attention as a naturally abundant and environmentally friendly and renewable resource.However,limited porosity and small functional groups of biomass will hinder its direct application.Therefore,it is of great significance toutilize the resource from biomass by means of activation and modification,and to orientallycontrol the preparation of functional carbon materials with well-developed pore structure and abundant functional groups.In this thesis,the methods of activation and modification of biomass based carbon materials,and their application in the field of removing bisphenol A in water and supercapacitor were researched.The mechanisms of activation and modification,and the mechanisms of adsorption of bisphenol A by carbon materials,as well as the influence of the physical and chemical properties of biomass based carbon materials on electrochemical storage performance were explored.The main contents and results of this thesis are listed as follows:(1)N doped carbon materials were prepared with sawdusts as raw material,sodium carbonate as activator and melamine as nitrogen source.The effects of sodium carbonate addition and nitrogen source addition on the structure and performance of the prepared carbon materials were studied.Experimental results show that sodium carbonate and melamine have a synergistic activation effect.As the amount of melamine added increases,BET surface area and total pore volume increases.As the amount of sodium carbonate added increases,the yield of carbon materials decreases and the BET surface area increases,indicating that the more sodium carbonate,the greater the degree of activation.The maximum adsorption capacity of the prepared N doped carbon materials for bisphenol A is up to 383.14 mg/g.In addition,the specific capacitance of the N doped carbon materials as the electrode material of the supercapacitor is up to 242 F/g at current density of 1 A/g,which has high rate performance and cycle stability.(2)Raw sawdusts and potassium thiocyanate were pyrolyzed to synthesize N/S codoped carbon materials.Potassium thiocyanate not only as a chemically activate reagent but also as nitrogen and sulfur sources.Experimental results show that the porous structure and π-π interactions play important roles on BPA adsorption towards N/S codoped carbons materials.In addition,Nitrogen and sulfur doping paly a synergistic role in improving adsorption performance.The maximum adsorption capacity of the N/S codoped carbon materials for bisphenol A is up to 502.51 mg/g.The specific capacitance of the carbon materials as the electrode material of the supercapacitor is up to 157 F/g at current density of 1 A/g,which has high rate performance and cycle stability.(3)N/S codoped carbon materials were fabricated via the potassium thiocyanate and melamine.The BET surface area of the carbon materials gradually increases,the nitrogen contents and sulfur contents gradually decrease with the activation temperature increases.The maximum adsorption capacity of the N/S codoped carbon materials for bisphenol A is up to 450.45 mg/g.When the activation temperature is 700℃,the specific capacitance of the carbon materials as the electrode material of the supercapacitor is up to 131 F/g at current density of 1 A/g.Experimental results show that BET surface area and N/S contents can improve specific capacitance of carbon materials.