Configuration jumps of rotor in a nanomotor from carbon nanostructures

Measuring the rotation of a rotor in a thermally driven motor made from double-wall carbon nanotubes (DWCNTs) involves challenges based in the small size of the nanotube (radius usually being less than or equal to 5 nm) and the high frequency of rotation (over 100 GHz). These features motivated us to study a rotor with variable configurations, in which the rotor is fabricated initially by bonding a graphene (GN) nanoribbon on a carbon nanotube (CNT). The width of the GN nanoribbon is far greater than the radius of the CNT. Using molecular dynamics simulation, we find that the “CNT + GN” rotor generally experiences three representative stages. In the first stage, the GN nanoribbon winds onto the CNT and the rotor becomes a carbon nanoscroll (CNS) within 100 ps (picoseconds). The second stage is acceleration of the rotor's rotation. The duration of that stage is controlled by the number of inward radial deviation (IRD) carbon atoms on the stator and the inertial moment of the rotor. When the rotational speed of the CNT reaches a critical value, the CNS unwinds within 80 ps into a nanoribbon, which can be considered as the third stage. When hydrogen atoms are initially added to the GN, more configuration variations of the rotor can be identified. The rotation of the “CNT + GN” rotor can be feasibly measured by observing the configuration variations of the rotor.