Use of Gemini surfactant as emulsion interface microreactor for the synthesis of nitrogen-doped hollow carbon spheres for high-performance supercapacitors

A series of N-doped porous carbon materials with open interconnected mesoporous shells and various mesoscopic morphology were synthesized by using the cationic Gemini surfactant pentane-1,5-bis(dimethylcetyl ammonium bromide) as the soft template through a sol-gel method and the mechanism of interfacial reaction was explored. The controllable morphological structure (particle size, shell thickness and interconnected structure of internal cavities in carbon nanospheres) can be easily achieved by simply adjusting the volume of ethanol and the amount of cationic Gemini surfactant. The synthesized N-doped mesoporous hollow carbon spheres (NMHCSs) exhibit the characteristics of small and tunable particle size (30–140 nm), ultrahigh surface area (1215–1517 cm 2  g −1 ) and large pore volume (1.12–3.22 cm 3  g −1 ), open interconnected hierarchical mesoporous (5–20 nm), high proportion doping of heteroatoms N (4.16–6.74 at.%) and O (6.17–8.68 at.%). The representative NMHCSs as electrical double layer capacitors electrodes in 6 M KOH electrolyte display an excellent electrochemical specific capacitance (240 F g −1 at 0.2 A g −1 ), superb capacitance retention (161 F g −1 at 20 A g −1 ), and excellent cycle stability (92% capacitance retention at 10 A g −1 after 5000 cycles). This research develops a simple synthesis strategy for a series of N-enriched carbon materials which exhibit promising application prospects for high-performance supercapacitors.