Silica-Assisted Assembly for Synthesis of Nitrogen-Doped Hollow Mesoporous Carbon Spheres as Supercapacitors

Abstract

Nitrogen-doped hollow mesoporous carbon spheres (NHMCSs) are synthesized by a one-pot silica-assisted assembly process and applied in supercapacitors. SiO2 spheres act as interior cores, which is crucial to form the hollow structure. 3-Aminophenol/formaldehyde resin and tetraethylorthosilicate (TEOS) cross-link through hydroxyl groups, then together directly deposit and co-assemble with cetyltrimethylammonium bromide via electrostatic interactions leading to an outer carbon-silica shell surrounding the SiO2 spheres. In the preparing process, TEOS not only acts as silica-assisted material and assembles with 3-aminophenol/formaldehyde resin, but also creates more pores to improve the surface area. After carbonization and silica etching, the NHMCSs with spherical morphology, uniform mesoporous, hollow structure, high surface area and nitrogen content are obtained. The nitrogen-doped, hollow and mesoporous structure are conducive to improve the capacitance. As electrode materials, the NHMCSs exhibit a high capacitance (201 F g−1 at 1 A g−1) and a good cycling stability (83.3% after 5000 cycles). These results reveal that NHMCSs can be expected to be promising electrode materials for electrochemical capacitors.