Structural properties and thermal stability of multi-walled black phosphorene nanotubes and their operation as temperature driven nanorotors

In this paper, we explore the influence of structural properties, thermal stability, and temperature on the rotational frequency of (0,n) armchair multi-walled black phosphorene nanotubes (MWβPNTs). Using Density Functional Theory (DFT) calculations, we first determine the influence of the outer wall rotation on the structural stability of (0,12)@(0,19) DWβPNTs, and (0,12)@(0,19)@(0,26) TWβPNTs. The results indicate that the relative energies of the DW- and the TWβPNTs do not change with the rotation angle. Therefore, the outer wall rotation is not important for the structural formation of the MWβPNTs. Then, using molecular dynamics (MD) simulations, we study the structural properties, thermal stability, and rotational frequency of (0,12)@(0,19) DWβPNTs, (0,12)@(0,19)@(0,26) TWβPNTs, and (0,12)@(0,19)@(0,26)@(0,33) QWβPNTs from 1 K to 400 K. The calorific curve, the mean-squared displacement, and the radial distribution function are analyzed to characterize the temperature behavior of the MWβPNTs. In all cases, the nanotubes are rotating: they act as thermal-driven rotors as the temperature increases, with a maximum rotational frequency of 16.7 GHz (clockwise direction) at 5 K for the DWβPNTs. Our results suggest that MWβPNTs could be used to construct room temperature nanomotors.