Facile one-pot hydrothermal synthesis of particle-based nitrogen-doped carbon spheres and their supercapacitor performance

A hierarchical porous structure is significant for carbon materials to achieve excellent performance in catalysis, separation, and energy applications due to its advantageous mass transport and high specific surface area properties. Herein, hierarchical porous particle-based nitrogen-doped carbon spheres (PNCSs) are prepared via carbonization of hydrothermal melamine-formaldehyde (MF) spheres in the presence of F127. F127 facilitates the nucleation of MF forming primary particles and stabilizes the primary particles. Later on in the process, the primary polymerized nanoparticles assemble into a micrometer-sized spherical structure. Thus, the textural features of MF/F127 composite microspheres are tuned by simply adjusting the amount of F127. After carbonization of the as-prepared MF/F127 microspheres, hierarchical porous microspheres composed of interconnected nitrogen-doped carbon nanoparticles with high specific surface area (1270 m² g^-1) are obtained. Owing to their unique structural feature and nitrogen-doping, PNCSs as electrode materials for supercapacitors exhibit enhanced electrochemical properties with remarkable specific capacitance (204.1 F g^-1 at 1 A g^-1, two-electrode system), high energy/power density and long cycling stability.