  Three typical one-dimensional (1D)/quasi-1D nanocarbons, linear carbon
chains, carbon nanotubes, and graphene nanoribbons have been proven to grow
inside single-wall carbon nanotubes. This gives rise to three types of hybrid
materials whose behaviour and properties compared among each other are far from
understood. After proving successful the synthesis of these nanostructured
materials in recently published work, we have now been able to study their
oxidation stability systematically by using resonance Raman spectroscopy.
Surprisingly, the linear carbon chains, which have been theoretically predicted
to be very unstable, are actually thermally stable up to 500 {\deg}C assisted
by the protection of the carbon nanotube hosts. Besides, longer linear carbon
chains inside narrower CNTs are more stable than the shorter ones inside larger
tubes, suggesting that the thermal stability not only depends on the length of
linear carbon chains alone, but it is correlated with the confinement of the
host tubes in a more complicated manner. In addition, graphene nanoribbons come
overall in view as the most stable confined structures. On the other hand,
peculiarities like the higher stability of the (6,5) CNT over its (6,4)
counterpart allow this study to provide a solid platform for further studies on
the application of these 1D nanocarbons (including true 1D linear carbon
chains) at ambient conditions.
