Hollow Carbon Spheres For Supercapacitor And Adsorbed Pollutants

Hollow carbon spheres(HCSs)are a noval type of carbon materials,with a size between nanometers and micrometers and a hollow structure and thin-walled shell.HCSs have the characteristics of stable structure,strong conductivity,high shell permeability,and large total pore volume.They have excellent performance in the fields of new energy electrode materials and environmental pollutant treatment.However,the current preparation method of hollow carbon balls still has the problems of complicated operation,low yild and secondary pollution,which is not suitable for large-scale production.Therefore,the purpose of this study is to use a carbon source with self-assembly characteristics,through a simple green high-yield method,a one-step method to directly prepare hollow carbon spheres with excellent electrochemical performance and pollutant adsorption capacity.The main findings are as follows.In this paper,?-cyclodextrin with self-assembly ability is used as the carbon precursor,and the aerosol spray method is used as the preparation method of the material,and the hollow carbon spheres are prepared in one step without using any template.In the preparation process,the self-assembly between?-cyclodextrin and ethanol is the key to forming a hollow structure,and the aerosol spray method ensures the particle size and dispersion of the material.And through TEM,SEM,nitrogen adsorption and desorption experiments,Zeta potential test,turbidity test and other methods to characterize and analyze the material.The characterization results show that HCSs have an average particle size of 1.1±0.6?m,a specific surface area of209.48 m~2/g,a pore volume of 0.523 cm~3/g,and excellent dispersion and low density.And the electrochemical performance of HCSs and the adsorption performance of pollutants were tested.The electrochemical performance of HCSs was characterized by CV,GCD,EIS,cycle performance test and other electrochemical characterization methods.The results show that:HCSs have a specific capacitance of 276 F/g at a current density of 0.2 A/g;HCSs have a good capacitance retention rate,and can still maintain a 70%specific capacitance at 50 times the current density;The cycle life of HCSs is excellent,and the charge and discharge are continuous3000 times under the condition of 2 A/g,and the specific capacitance is still 92.3%of the initial value;In addition,HCSs also have excellent electrochemical reversibility and extremely low internal resistance.In addition,the adsorption capacity of HCSs to Zn(?),methylene blue,phenanthrene and other environmental pollutants was also studied.The effects of the initial dose of HCSs,the initial pH of the solution on the adsorption of three pollutants and the recycling performance of HCSs adsorbed pollutants are also discussed.The experimental results show that HCSs have better adsorption properties for the above pollutants than solid carbon spheres,which can be attributed to its higher specific surface area and pore volume and longer suspension time in water.The HCSs of 2,3,and 4 g/L achieved 100%removal rate of 20 mL of 25 mg/L Zn(?),methylene blue,and phenanthrene solutions,respectively.After five cycles of adsorption,the removal rates of Zn(?),methylene blue,and phenanthrene solutions can be maintained at 77%,69%,and 86%,respectively.