In the present work, we have demonstrated a simple but effective template carbonization approach to convert folic acid into highly nitrogenated nanoporous carbon materials, using Mg(OAc)(2)center dot 4H(2)O as template. For the C-800/900/1000 samples, the nitrogen contents can reach up to 9.03%, 6.81%, and 6.65%, respectively, and they also deliver large BET surface areas of 1242.2, 1559.1, and 1302.8 m(2) g(-1), and high pore volumes of 136, 2.26, and 1.44 cm(3) g(-1), respectively. On the other hand, it is revealed that the incorporation of p-phenylenediamine as a redox additive into KOH electrolyte has greatly improved the capacitances, mostly due to the occurrence of pseudo-capacitance derived from the redox reaction of p-phenylenediamine at the electrode/electrolyte interface. For instance, the capacitances of the C-900-6/9/12 samples can reach up to 105.1, 232.8, and 317.6 F g(-1) at 5 A g(-1), respectively, and all of which are much higher than that of the pristine C-900 sample (42. F g(-1)). Obviously, we have provided a simple but highly efficient approach for the improvement of the supercapacitor capacitance by introducing the p-phenylenediamine into KOH electrolyte, which exhibits the advantages of low cost, easy operation, high efficiency, etc. (C) 2016 Elsevier B.V. All rights reserved.