Fabrication of nitrogen-rich three-dimensional porous carbon composites with nanosheets and hollow spheres for efficient supercapacitors

Abstract

N-Doped carbon materials have shown great potential in energy-related areas, but well-controlled doping of nitrogen and components along with fine-construction of multidimensional porous architectures remains a great issue. Herein, we demonstrate a temperature-directed strategy to fabricate nitrogen-rich three-dimensional (3D) porous carbon composites with nanosheets and hollow spheres for efficient supercapacitors. Polydopamine@SiO₂ core–shell spheres were first fabricated through a one-step synthesis method followed by mixing with dicyandiamide and glucose to form a uniform precursor. After pyrolysis of the precursor at a high temperature and etching of SiO₂ cores, the hollow carbon spheres were successfully inserted into the carbon sheets and finally 3D porous hybrids were obtained. The nitrogen doping content and compositions of carbon hybrids can be controlled through adjusting the pyrolysis temperature. The as-prepared 3D carbon material with a nitrogen content of 23.2 wt% and abundant mesopores exhibits a superior specific capacitance of 425 F g⁻¹ at 1 A g⁻¹ and maintains 248 F g⁻¹ even at a high current density of 80 A g⁻¹ in 6 M KOH electrolyte. Our work provides a feasible and general approach to design and synthesize porous nitrogen-rich 3D carbon-based electrode materials for efficient supercapacitors.