The preparation of mesoporous activated carbon by microwave radiation heating walnut shell

The mesoporous activated carbon was prepared by microwave radiation process using walnut shell as carbon source. The as-prepared activated carbon was well characterized by XRD, SEM and nitrogen adsorption-desorption. The influences of microwave power and radiation time on the capacitance characteristics of activated carbon for electrochemical capacitors was investigated by glavanostatic charge-discharge, cyclic voltammetry (CV)and AC impedance spectroscopy. Microwave power at 480 W and radiation time for 9 min were regarded as the optimum process.The activated carbon prepared under this process had the average pore size of 4.44 nm and the mesoporous rate of 78.51%. The specific surface area was 1 530 m2/g and its shape was irregular, porous and amorphous structure. The specific capacitance was 226.4 F/g at the charge-discharge current of 100 mA/g. It kept 192.2 F/g after 1 000 cycles, and the capacity fade of activated carbon was only 0.015% when cycled at 100 mA/g.