Molecular motor constructed from a double-walled carbon nanotube driven by axially varying voltage

A new molecular motor is conceptually constructed from a double-walled carbon nanotube (DWNT) consisting of a long inner single-walled carbon nanotube (SWNT) and a short outer SWNT with different chirality. The interaction between inner and outer tubes is the sum of the Lennard-Jones potentials between carbon atoms in an inner tube and those in an outer one. Within the framework of the Smoluchowski-Feynman ratchet, it is theoretically shown that this system in an isothermal bath will exhibit a unidirectional rotation in the presence of a varying axial electrical voltage. Moreover, the possibility of manufacturing this electrical motor from DWNT is discussed under the current conditions of the experimental technique.

Figure 1

(Color online) Schematic diagram of the DWNT motor driven by varying electrical field. The DWNT consists of a long inner tube and a short outer tube. It is put between a pair of electrodes with a varying voltage $\tilde{U}\left(t\right)$ applied on.

Figure 2

(Color online) Interactions between the outer tube and the inner tube with different lengths of carbon-carbon bonds. Here the potentials $V(0,a_{cc})$ are set to zero by subtracting some constants.

Figure 3

Average dimensionless angular velocity $⟨d\theta ∕d\tau ⟩$ of the outer tube rotating around the inner one in isothermal bath when the varying axial voltage with dimensionless period $\mathcal{J}$ is applied. A negative number means clockwise rotation around the $z$ axis while a positive number represents counterclockwise rotation.