In spite of the current prevalence of the CVD-based processes, the electric arc remains an interesting process for the synthesis of carbon nanoforms, thanks to its versatility, robustness and easiness. It also allows ...In spite of the current prevalence of the CVD-based processes, the electric arc remains an interesting process for the synthesis of carbon nanoforms, thanks to its versatility, robustness and easiness. It also allows performing in-situ substitution of carbon atoms by hetero-elements in the graphene lattice. Our work aims to establish a correlation between the plasma properties, type and chemical composition （and the substitution rate） of the obtained single-wall carbon nan- otubes. The plasma was characterized by optical emission spectroscopy and the products were analyzed by high resolution transmission electron microscopy and core level Electron Energy-Loss Spectroscopy （EELS）. Results show that a high boron content leads to a plasma temperature decrease and hinders the formation of nanotubes. This effect can be compensated by increasing the arc current and/or yttrium content. The optimal conditions for the synthesis of boron- and/or nitrogen-substituted nanotubes correspond to a high axial plasma temperature associated to a strong radial gradient. EELS analysis confirmed that the boron incorporates into the graphenic lattice.展开更多
文摘In spite of the current prevalence of the CVD-based processes, the electric arc remains an interesting process for the synthesis of carbon nanoforms, thanks to its versatility, robustness and easiness. It also allows performing in-situ substitution of carbon atoms by hetero-elements in the graphene lattice. Our work aims to establish a correlation between the plasma properties, type and chemical composition （and the substitution rate） of the obtained single-wall carbon nan- otubes. The plasma was characterized by optical emission spectroscopy and the products were analyzed by high resolution transmission electron microscopy and core level Electron Energy-Loss Spectroscopy （EELS）. Results show that a high boron content leads to a plasma temperature decrease and hinders the formation of nanotubes. This effect can be compensated by increasing the arc current and/or yttrium content. The optimal conditions for the synthesis of boron- and/or nitrogen-substituted nanotubes correspond to a high axial plasma temperature associated to a strong radial gradient. EELS analysis confirmed that the boron incorporates into the graphenic lattice.
