Preparation of activated carbons
The coconut-shells used as carbon precursors, were cut
into 3 cm×3 cm×3 cm small blocks, washed with deionized
water for several times, and then put into an oven at 105 ◦C
for 24 h before carbonization. The dry coconut-shells were
transferred into a carbide furnace and carbonized at 600 ◦C
for 3 h under a nitrogen atmosphere with the heating rate of
10 ◦C/min. The carbonizations were fabricated by the following
three ways