Fig. 2

a The three-dimensional motion trajectory of a C atom on carbon nanotube. The hydroxyl groups’ ratio on carbon nanotube and Si substrate is 10 and 20%, respectively. b The coordinate of a C atom on carbon nanotube in the z direction as a function of time. The hydroxyl groups’ ratio on carbon nanotube and Si substrate is 5%/5%, 5%/10%, 10%/10%, and 10%/20%, respectively