Preparation And Electrochemical Performance Of Novel Carbon Materials Based On Polydopamine

Porous carbon materials have been widely used as electrode materials for supercapacitors due to their high specific surface area,excellent electron conductivity and good chemical stability.However,compared with other types of electrode materials,such as metal oxides and conducting polymers,the specific capacitance and energy density of carbon based electrode materials are still low.In order to improve the electrochemical performance of porous carbon materials,an effective method is to dope the heteroatoms and functional groups into the carbon skeleton.Compared with the pure porous carbon materials,nitrogen doping can improve the conductivity and wettability of the material.However,the preparation process is time-consuming or dangerous,and the activation process is easy to pollute the environment.Therefore,it is important to study porous carbon material with an environmental friendly preparation process and better electrochemical performance for the development of electrode materials.N-doped porous carbon materials mainly store charges via the accumulation of the charge in the electrolyte and electrode surface and the redox reaction of surface containing nitrogen functional groups.They have the characteristics of large specific surface area,good cycle stability and so on.However,this kind of material often has low nitrogen doping rate,complicated preparation process and environmental pollution,which limit their practical application.Herein,polydopamine(PDA)spheres with an average particle size of 650±38nm were prepared through the self-polymerization of biological small molecule dopamine under alkaline conditions.Then the nitrogen doped porous carbon materials were obtained by carbonized PDA spheres at high temperature with the presence of activator KOH,thus avoiding the complicated process of nitrogen doping and the application of hard template.The surface morphology,structure and composition of the obtained N-doped porous carbon materials were characterized by SEM,TEM,XRD,FT-IR,XPS and Raman spectroscopy,respectively.The effects of carbonization temperature on the structure,pore morphology and electrochemical properties of the materials were systematically investigated.The surface area and pore volume ofPDA-KOH-700 prepared using KOH as activator and carbonization at 700 ℃ can reach 1469.49 m2g-1 and 0.8527 cm3g-1 respectively.The electrochemical performances were investigated by cyclic voltammetry and galvanostatic charge/discharge in 6 mol·L-1 KOH electrolyte.The results show that the specific capacitance of the material could reach 269 F/g at the current density of 1 A/g because of the synergistic effect of double layer capacitance and pseudocapacitance.The capacitance still remained 93.5% after the cycle of 1000 cycles.These results demonstrate that PDA-KOH-700 could serve as a promising candidate for the electrode material of high-performance supercapacitor.