Porous Carbons Prepared from Polyacrylonitrile Doped with Graphitic Carbon Nitride or Melamine for Supercapacitor Applications

Graphical Nitrogen-doped porous carbons were prepared by pyrolysis of polyacrylonitrile films doped with melamine or graphitic carbon nitride obtained by thermal condensation of melamine. Compared with melamine, g-C 3 N 4 was more efficient in nitrogen doping and porous structure, which mainly resulted from the high thermostability and large size of the dopant, thus enhancing the supercapacitor performance. Melamine and graphitic carbon nitride (g-C 3 N 4 ) obtained by thermal condensation of melamine were doped in polyacrylonitrile (PAN) films. Nitrogen-doped porous carbons were then prepared by pyrolysis of the composite films. Though all the porous carbons had a high nitrogen content of at least 10 %, g-C 3 N 4 was more efficient than melamine in nitrogen doping. The nitrogen content was elevated with the increase of the amount of each dopant, the highest value of 19.0 % was achieved by g-3 (porous carbon obtained from the PAN/g-C 3 N 4 composite film with a mass ratio of 3). Amongst the nitrogen functionalities, pyridinic-N and pyrrolic-N held a percentage of at least 80 %. Compared with the carbon materials obtained from melamine doped PAN films, those from g-C 3 N 4 doped ones exhibited larger surface area and average pore size, and higher pore volume. The difference mainly resulted from the thermostability and size of the dopants. The g-C 3 N 4 doped materials thus presented more excellent electrochemical properties. The specific capacitance of g-3 electrode was 135.3 F/g at a current density of 0.5 A/g. Rather than melamine, g-C 3 N 4 could improve the chemical composition and textural properties of the carbon materials, thus enhancing their supercapacitor performance.