Synthesis of nano onion-like fullerenes by using Fe/Al2O3 as catalyst by chemical vapor deposition

Nano-carbon materials were synthesized by the catalytic decomposition of acetylene at 400°C by using Fe/Al₂O₃ as catalyst. The product was refluxed in 36% concentrated HCl at 60. for 48 h in order to remove the catalyst support. The samples were examined by scanning and high resolution transmission electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results show that nano onion-like fullerenes encapsulating a Fe₃C core were obtained. These had a structure of stacked graphitic fragments, with diameters ranging from 15–50 nm. When the product was further heattreated at 1100°C for 2 h, nano onion-like fullerenes with a clear concentric graphitic layer structure were obtained. The growth mechanism of nano onion-like fullerenes encapsulating metal cores is suggested to follow a vapor-solid growth model. Supported by National Natural Science Foundation of China (Grant Nos. 20471041, 20676086 and 20673072)