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

Melamine and graphitic carbon nitride (g-C3N4) 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-C3N4 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-C3N4 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-C3N4 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-C3N4 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-C3N4 could improve the chemical composition and textural properties of the carbon materials, thus enhancing their supercapacitor performance. 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-C3N4 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.image