Self-catalyzed strategy to form hollow carbon nanospheres for CO2 capture

• Hollow carbon nanospheres (HCNs) are synthesized via self-catalyzed method.
• The NH2–SiO2 nanospheres are used as template and catalyst simultaneously.
• This method provides a general process for the formation of HCNs.

The hollow carbon nanospheres (HCNs) are synthesized by self-catalyzed method. The amino-functionalized silica nanospheres (NH2–SiO2) play the roles of template and catalyst. As a basic group, the amino provides slight alkaline conditions which can catalyze the polymerization of resorcinol-formaldehyde (RF) resin. Additionally, the amino group covering the outer surface of SiO2 turns to be slight positively charged in the solution, which allows deposition of negatively charged RF on the surface of NH2–SiO2. The method has an advantage over previous method in terms of environment protection due to the absence of surfactant and ammonia. After carbonization and removal of the SiO2 templates, the obtained HCNs completely copy the morphology of SiO2, exhibiting uniform and monodispersed spherical structures with the diameter of ~290 nm and surface area of 777 m2 g−1. The sample exhibits a performance for CO2 capture with the capacity of 3.65 mmol g−1 at 298 K and 1.0 bar after activation with KOH.