关键词: 小麦面粉, 草酸钾, 尿素, 3D多级孔炭, 超级电容器, 电极材料

Abstract:

Nitrogen/oxygen co-doped 3D hierarchical porous carbons with ultra large specific surface area were prepared from wheat flour in the presence of potassium oxalate/urea solution on the basis of its good swelling and permeation effects on starch grains. The experimental results indicated that when the mass ratio of wheat flour to potassium oxalate was 1∶1.5, the pore structure and surface physicochemical properties of porous carbon materials could be effectively optimized by adding proper amount of urea as pore forming agent and dopant. The maximum specific surface area of the porous carbon samples prepared was 3192m²/g, and its micropore and mesopore volumes were 1.48cm³/g and 0.55cm³/g respectively. In the three electrode system, the electrochemical analysis results indicated that the specific capacitance of the porous carbon electrode sample KNPC-7.5-7.5 could reach 284F/g with an ideal rate performance when the current density was 0.5A/g. A button-type symmetric supercapacitor was assembled by using KNPC-7.5-7.5 sample as electrode material to evaluate the electrochemical energy storage performance. The sample electrode offered excellent cyclic performance with 95.6% capacitance retention after 5000 times cyclic charge and discharge at a current density of 5A/g. Moreover, the self-made supercapacitor showed a high energy density of 23.7Wh/kg at a power density of 223.6W/kg.

Key words: wheat flour, potassium oxalate, urea, 3D hierarchical porous carbon, supercapacitor, electrode material