AbstractIn this paper, a novel molecular dynamic model is presented to describe the growth mechanism of three-dimensional (3D) graphene-carbon nanotube (G-CNT) hybrid structure synthesized by catalytic chemical vapor deposition. For this purpose, first, the physisorption of a carbon atom on a graphene sheet (GS) is studied. Then the model is formulated by using kinetic theory and the longitudinal phonon oscillation of adsorbed carbon atoms on GS. Results show that the CNT grows on GS up to 0.3 mm. Also, there is an optimum temperature for growth of the 3D G-CNT hybrid structure, which can be calculated by the presented model. Finally, it is shown that increase of partial pressure leads to increase of length of growing CNT on GS.