Preparation of nitrogen-doped graphitic porous carbon towards capacitive deionization with high adsorption capacity and rate capability

A facile strategy was proposed to synthesize nitrogen-doped graphitic carbon polyhedrons (NGCPs) with high sp-2 skeleton edges by direct pyrolysis of zeolitic immidazolate frameworks (ZIF-8) in low pressure and nitrogen atmosphere. The NGCPs not only maintains typical polyhedrons shape, but also owns remarkable specific surface area of 1134 m(2)/g, high N content of and high graphitization degree. The electrochemical behaviour of NGCPs demonstrated the superiority in specific capacitance and cycling ability, as well as electrical conductivity. When it was employed as electrode capacitive deionization (CDI), the maximum salt removal capacity of NGCPs up to 17.73 mg/g in 500 mg/L NaCl solution at the cell voltage of 1.4 V. Besides, the NGCPs possess high salt adsorption rate of 4.14 mg/g.min and good regeneration performance. The enhancement on CDI performances are attributed to the high specific surface area, high graphitization, nitrogen doping as well as an elevated electrical conductivity.