The Raman spectrum of nano-structured onion-like fullerenes

Onion-like fullerenes (OLFs) have been studied by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. With a precise control of current, high-quality OLFs with few defects are found on the redeposit rod on the cathode. The size of OLFs is found to be in the range of 15-40 nm. Metal particles are useful support crystal to realize the synthesis of high-quality OLFs. Raman spectra of OLFs show high degree of graphitization. Compared with that of highly oriented prolific graphite (HOPG), the strain of graphene planes due to curvature and uneven distribution of the diameter of OLFs has been estimated analytically and is used to account for the downward shift of the G peak.