Controllable synthesis of N-doped hollow-structured mesoporous carbon spheres by an amine-induced Stöber-silica/carbon assembly process

We have demonstrated a facile and controllable synthesis of N-doped carbon spheres by an amine-induced Stöber-silica/carbon assembly route. In this process, ethylenediamine (EDA), as both a base catalyst and nitrogen precursor, is introduced into a Stöber-silica/carbon assembly system for the first time. Moreover, carbon materials with different nanostructures, including yolk-shell mesoporous carbon spheres (YSMCSs) and hollow mesoporous carbon spheres (HMCSs), are obtained by changing the amount of EDA. The resultant carbon nanospheres possess high surface areas (up to 2001 m² g^-1), large pore volumes (up to 1.86 cm³ g^-1) and uniform mesopore size (∼2.6 nm for N-YSMCSs, ∼2.4 nm for N-HMCSs). The obtained two kinds of carbon spheres manifest excellent supercapacitor performances with high capacitance, favorable capacitance retention, and unprecedented cycling stability, which may be contributed to by the hollow large surface area, high porosity, mesoporous structures, and N heteroatomic functionality. We believe that such structure integrations are useful for a lot of applications, such as advanced energy storage materials and catalyst supports.