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

Abstract

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.