Preparation of activated mesoporous carbons for electrosorption of ions from aqueous solutions

Mesoporous carbon with a narrow pore size distribution centered at about 9 nm, which was prepared by self assembly of block copolymer and phloroglucinol-formaldehyde resin via the soft-template method, was activated by CO(2) and potassium hydroxide (KOH). The effects of activation conditions, such as the temperature, activation time, and mass ratio of KOH/C, on the textural properties of the resulting activated mesoporous carbons were investigated. Activated mesoporous carbons exhibit high BET specific surface areas (up to similar to 2000 m(2) g(-1)) and large pore volumes (up to similar to 1.6 cm(3) g(-1)), but still maintain a highly mesoporous structure. Heat treatment of mesoporous carbons by CO(2) generally requires a moderate to high extent of activation in order to increase its BET surface area by 2-3 times, while KOH activation needs a much smaller degree of activation than the former to reach an identical surface area, ensuring high yields of activated mesoporous carbons. In addition, KOH activation allows a controllable degree of activation by adjusting the mass ratio of KOH/C (2-8), as evidenced by the fact that surface area and pore volume increase with the mass ratio of KOH/C. The electrosorption properties of activated mesoporous carbons were investigated by cyclic voltammetry in 0.1 M NaCl aqueous solutions. Upon activation, the electrosorption capacitance of activated mesoporous carbons was greatly enhanced.