Molten salt synthesis of hierarchical porous N-doped carbon submicrospheres for multifunctional applications: High performance supercapacitor, dye removal and CO2 capture

Hierarchical porous N-doped carbon submicrospheres (HPNCs) are synthesized at 1000 degrees C by a facile molten salt method using diaminomaleonitrile as a precursor, iron trichloride as a catalyst, and ZnCl2-KCl to form the molten salt medium. The results indicated that the pore structure of resultant HPNCs could be tuned by changing the amount of iron catalyst, and those prepared with adding 7.1 wt% FeCl3 center dot 6H(2)O showed the highest specific surface area (3155 m(2)/g) and largest hierarchical pore volume (2.2 cm(3)/g) with micropore and mesopore surface areas of 808 m(2)/g and 2347 m(2)/g, respectively, in addition to their high mesopore ratio up to 84.4%. The resultant HPNCs showed outstanding specific capacitance up to 455 F/g in 6 M KOH electrolyte solution at a current density of 0.5 A/g, a considerably high energy density of 93.6 Wh/kg and high capacitance retention of 95% after 5000 cycles. Moreover, they exhibited high adsorption capacities of 812.2 mg/g and 805.2 mg/g, for methylene blue and methyl orange adsorption, respectively, and high CO2 adsorption capacity of 3.4 mmol/g at 25 degrees C and at an equilibrium pressure of 1 bar. (C) 2018 Elsevier Ltd. All rights reserved.