N-doped honeycomb-like hierarchical porous carbon foams for supercapacitor applications with different PC/RF mass ratios

The use of heteroatoms-doped carbon foams materials with well-organized pores as supercapacitor electrodes has always been of great interest. Nevertheless, the preparation of these materials is often a complex process, involving several steps. In this work, we present a facile and free template method based on an oil-in-water emulsion to synthesize N-doped hierarchical porous carbon foams (N-HPCFs) with a large specific surface area and high pore volume. The unique structure and excellent chemical properties of the obtained material resulted from the synergistic effects of the potassium citrate (PC) and the hydrogen bonds formed between carbon precursor (resorcinol/formaldehyde resin (RF)) and nitrogen precursor (melamine). The experimental results revealed that the PC/RF mass ratio has an influence on the material structure and properties. Therefore, when this mass ratio was 1: 2.5, a material (N-HPCFs-2.5) with a large specific surface area (1759 m(2)/g) and pore volume (0.83 cm(3)/g) was obtained. As electrode for supercapacitors, N-HPCFs-2.5 exhibited a high specific capacitance up to 298 F/g at 1 A/g in a three-electrode system and using 6 M KOH electrolyte. Also, it exhibited a good stability with a capacitance retention of ~ 90% after 5000 cycles at 1 A/g. Therefore, the N-doped hierarchical carbon foams are promising high-performance electrodes for energy storage devices.