Theoretical study of the reduction in sensitivity of copper azide following encapsulation in carbon nanotubes

Research aimed at reducing the sensitivity of primary explosives with excellent ignition performance is of great significance for their practical application. In this work, we theoretically studied the effect of inserting the primary explosive copper azide (Cu(N₃)₂) into single-walled carbon nanotubes (SWCNTs) on the sensitivity of the explosive to changes in hydrostatic pressure. The electronic structure of Cu(N₃)₂ was found to be more sensitive to external pressure than lead azide, which is consistent with their experimental impact sensitivities. A composite of Cu(N₃)₂ molecules and SWCNTs (Cu(N₃)₂/CNTs) was prepared in which the components mainly interacted electrostatically and the Cu(N₃)₂ molecules formed semi-arc structures along the nanotube walls, rather than exhibiting their usual planar structure. The electrostatic potential and electronic structure of the composite indicate that it is more stable than crystalline Cu(N₃)₂. Notably, combining the Cu(N₃)₂ with the SWCNTs reduces the sensitivity of the Cu(N₃)₂ to external pressure, implying that carbon nanotubes can reduce the sensitivity of Cu(N₃)₂. This work should aid the development of highly efficient green primary explosives.