Enhanced electrical capacitance of porous carbons by nitrogen enrichment and control of the pore structure

A series of nitrogen-containing porous carbons were produced through KOH activation of a nitrogen-enriched carbon prepared in the pores of a mesoporous silica. Nitrogen sorption at 77 K showed that the pore volumes increased gradually along with an increasing mass ratio of KOH/carbon. The sample with the highest pore volume of 2.68 ml g−1 was obtained when the mass ratio was 5. Cyclic voltammetry was employed for determination of the electrochemical properties. These samples exhibited a very promising potential as electrode materials for electrical double layer capacitors. An optimized electrical capacitance of 318 F g−1 was obtained in a 6 M KOH electrolyte when the mass ratio KOH/carbon was 3. The effect of the nitrogen content of the samples on the activation behavior and electrochemical properties are discussed in detail.