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Hollow graphitic carbon nanoparticles (HGCNs) obtained by catalytic graphitization of acetylene carbon black (ACB) were investigated using ultra-soft X-ray emission spectroscopy. The electronic structures of the ACB HGCNs were compared with those of HGCNs obtained from iron carbide-filled carbon nanocapsules (Fe3C@CNCs) and Q-graphenes. The occupation of the π sub-band decreased in the following sequence: Fe3C@CNC HGCNs > ACB HGCNs > Q-graphenes. This sequence can be explained by changes in the occupations of the C2p states due to the formation of bonds between carbon and residual metal atoms within the HGCNs. It was also found that the contribution of the overlapping ofppπ+ppσ-states in the ACB HGCN walls toward the spectra of the HGNCs was greater in comparison with the reference Q-graphenes. It was established that ACB was not fully transformed into the HGCNs. Scanning and transmission electron microscopy methods were used to study the spatial structures and morphologies of the fabricated HGCNs. [ABSTRACT FROM PUBLISHER]

Hollow graphitic carbon nanospheres (HGCNSs) obtained by treatment of iron carbide-filled carbon nanocapsules were investigated using the ultra-soft X-ray emission spectroscopy method. Carbon nanocapsules were synthesized by the plasma discharge method in an ultrasonic cavitation field of liquid hexane. It was revealed that additional mixed π + σ -overlapping occurred in the hollow graphitic carbon nanospheres as a result of the bending of the graphene sheets. Some iron atoms remained after washing in acid. It was found that in the hollow graphitic carbon nanospheres, sp- hybrid bonds formed between the carbon and residual iron atoms when high-energy 3 d + 4 s -states overlapped with sp n -hybrid orbitals (2 < n < 3). Scanning and transmission electron microscopy methods were used to study the spatial morphology and structure of the fabricated HGCNSs. The electronic structures of the HGCNSs were compared with those of reference synthetic graphite powder, carbon onions, and graphene nanosheets. [ABSTRACT FROM AUTHOR]