Nitrogen-doped hollow carbon spheres from bio-inspired dopamine: Hexamethylenetetramine-induced polymerization, morphology control and supercapacitor performance

Through a one-pot carbonization route, nitrogen-doped hollow carbon spheres (NHCS) with adjustable surface topography were manufactured by using dopamine as carbon and nitrogen source, melamine-formaldehyde (MF) nanospheres as template, and hexamethylenetetramine as pH buffer. During carbonization process, the MF core decomposed to form a hollow structure, and meanwhile introduce nitrogen into the carbon skeleton and activated the carbon shell. By tuning the concentration of dopamine monomers, the obtained NHCS exhibited deflated-ball like or spherical morphology with high surface areas of 865-1307 m2 g-1 and dual-mesoporous (2.6 and 3.8 nm) structure. Benefiting from the hollow structure, hierarchical porous shell and nitrogen doping, the all-solid-state supercapacitors assembled by NHCS showed high energy density of 6.1 Wh kg-1 at 100 W kg-1, high rate performance as well as long cycle life of 83.3% capacitance retention after 5000 cycles.

Automated summary

Nitrogen-doped hollow carbon spheres (NHCS) with adjustable surface topography were synthesized using a one-pot carbonization route, exhibiting deflated-ball like or spherical morphology with high surface areas and dual-mesoporous structure. The NHCS-based supercapacitors showed high energy density, rate performance, and long cycle life, thanks to their hollow structure, hierarchical porous shell, and nitrogen doping.