sp2-sp3 Hybridized Carbons from Curved Carbon Precursors of Fullerenes and Single-Walled Carbon Nanotubes

sp²-sp³ hybridized carbons have garnered attention for their diverse configurations and tunable properties. However, the atomic-level transformation mechanism, particularly the precursor configurations and the six-membered (6-M) ring ratio, remains not fully understood. This study investigated the phase transformations of fullerenes (C₂₀, C₆₀, C₇₀) and single-walled carbon nanotubes (SWCNTs) into sp²-sp³ hybridized carbon using molecular dynamics simulations. Fullerenes transform into amorphous carbon, while SWCNTs evolve into graphite-diamond hybrids with a semicoherent interface. Temperature controls product type, and pressure modulates sp³/sp² ratio. A higher 6-M rings ratio in fullerene precursors increases the structural order manifested by graphite and diamond-like characteristics. A “pinning effect” caused by edge dislocations in SWCNTs facilitates the semicoherent interface formation by increasing the interlayer spacing and altering the stacking order of graphite. The proposed sp²-sp³ hybridized carbons demonstrate tunable mechanical properties. This study advances our understanding of the atomic-level mechanism underlying sp²-sp³ hybridized carbon transformations and their potential applications.