The fabrication of size-tunable nitrogen-doped dual-mesoporous carbon nanospheres with excellent thermal stability via colloidal silica driving co-assembly strategy

The synthesis of nitrogen-doped dual-mesoporous carbon nanospheres (N-DMCNs) with tunable sizes remains a great challenge due to the high cross-linking rate of carbon precursors and the weak interactions among the carbon precursors, inorganic components and templates. Herein, we demonstrated a colloidal silica nanoparticles (SN) driving co-assembly strategy for the first time to fabricate such N-DMCNs with hydrochloric acid (HCl) as a catalyst. Interestingly, SN not only acted as a pore-forming agent but also as a driving agent to induce the co-assembly of F127, carbon precursors and SN. The affinity between carbon precursor and template was enhanced by the Coulombic interaction originating from the I+X−S+ mechanism driven by the protonation under highly acidic conditions. Furthermore, the mesoporous structure and particle sizes could be facilely tuned by varying the HCl concentration, which was elucidated by both reversible reaction and nuclei growth mechanism. The as-prepared N-DMCNs could be potentially used as drug carrier for poorly water-soluble drug carbamazepine by improving its aqueous release rate. Compared with previously reported method, the present strategy has striking features such as convenient, inexpensive and environmentally friendly, especially affording a paradigm for the preparation of spherical mesoporous carbon nanoparticles through driving-induced assembly engineering.

Colloidal silica (SN) driving co-assembly strategy was first demonstrated to fabricate N-DMCNs. HCl was used as a catalyst for the polymerization of 3-aminephenol (AP) and formaldehyde at an initial temperature of 35 °C. It could be found that, by the addition of SN, the well-defined dual-mesoporous structure (3.5 and 7.8 nm) was obtained. Therefore, SN not only acts as a pore-forming agent but also as a driving agent to induce the participation of F127 into the assembly process. By optimizing the fabrication parameter, the resulting N-DMCNs exhibited the tunable sizes, excellent thermal stability and large specific surface. Compared with previously reported method, the present strategy could afford a paradigm for the preparation of spherical carbon nanoparticles with mesoporous structure through driving-induced assembly engineering.249