Preparation of hollow mesoporous carbon spheres by pyrolysis-deposition using surfactant as carbon precursor

Hollow mesoporous carbon spheres (HCS) are widely used in many fields, such as supercapacitors, adsorption, separation, batteries, etc., due to their large specific surface area, large cavity, thin mesoporous shell and good chemical stability. Herein, N-doped HCS was prepared using the pyrolysis-deposition method, with cetyltrimethylammonium bromide (CTAB) micelles derived from a hard template of solid silica core coated with mesoporous silica (SiO2@mSiO2), as the carbon and nitrogen precursor. This method realizes direct carbon formation from the decomposable surfactant CTAB, which avoids the need for other carbon precursors and simplifies the preparation process. The mesopores on the SiO2@mSiO2 template shell provide limited space and the transition metals provide active sites, which promotes the deposition of carbon derived from surfactants. The shell thickness of HCS can be adjusted by the thickness of the SiO2@mSiO2 template shell, which leads to a change in the morphology, i.e. from imperfect (macropore) hollow spheres to complete hollow spheres and transformation of the surface from rough to smooth. Ultimately, the resultant HCS completely replicates the morphology of the template and shows a uniform spherical shape with a mesoporous shell, a cavity, a high specific surface area and suitable N-doping content, which ensures good electrochemical performance as an active electrode material in supercapacitors.