A mild molecular fusion route for the synthesis of polyhedral carbon nano-onions with high graphitization

Polyhedral carbon nano-onions (CNOs) compared with traditional quasi-spherical CNOs are more stable and have less defects, which will greatly broaden their potential applications. However, there still lacks of a suitable synthetic method. Here, we developed a simple molecular fusion route and templet growth method by which polyhedral CNOs can be successfully synthesized. Characterization of the polyhedral CNOs by transmission electron microscopy, x-ray diffraction and Raman spectroscopy indicates that they have an ultra-high degree of graphitization and a large cavity diameter of about 10 nm, which results in their low density of 1.42 g cm^-3. In addition, the deeper reaction mechanism of polyhedral CNOs growth was also elucidated. It was found that the channel structure and the absorption of the templet play the crucial role during the formation of polyhedral CNOs.