We have studied computationally the bond dissociation enthalpy (BDE), the formation enthalpy and the local electronic properties of Single-Walled Carbon Nanotubes (SWCNT). The arm-chair (i.e. CNT(n,n) where n= 3,4,5,6,7) and zig-zag (i.e. CNT(m,0) where m=6,7,8,9,10) chirality CNT, with various lengths (i.e. 9.0-36.2 Å) and diameters (i.e. 4.2-9.6 Å), were considered. The dangling bonds in these SWCNT were terminated with H-atoms. Our analysis shows that there is a strong quantum-size effect on the BDE and the formation enthalpy of these SWCNTs, which is inversely proportional to the curvature-squared (1/r2) and inversely proportional of the SWCNT length (1/l). This suggests that SWCNT become less stable as their length increases due to the emergence of metallic properties and as their radius decreases, which is due to smaller overlap of the p orbitals. This clearly shows that there is a quantum-size effect of the thermodynamic properties of SWCNTs when their length and diameter is less than 4 nm.

Quantum-size effect of the bond dissociation enthalpies and formation enthalpies in single walled carbon nanotubes

2019 Fall National Meeting

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