Dispersion $C_3$ coefficients for physisorption of heavy ions and atoms with graphene and carbon nanotubes

TL;DR

This study calculates dispersion $C_3$ coefficients for heavy ions and atoms interacting with graphene and carbon nanotubes, revealing graphene's superior suitability for adsorbing toxic heavy elements based on van der Waals interactions.

Contribution

The paper introduces a method to evaluate dispersion $C_3$ coefficients for heavy elements with graphene and nanotubes using Lifshitz theory and Dirac model, including dynamic polarizabilities.

Findings

Graphene shows higher $C_3$ coefficients, indicating stronger dispersion interactions.

Dispersion coefficients vary with nanotube radius and gap parameter.

Graphene is more effective than nanotubes for adsorbing heavy toxic elements.

Abstract

In the present work, the calculations have been performed for dispersion interaction between heavy elements (Zn$^+$, Cd$^+$, Hg$^+$, Pb$^+$, Zn, Cd, Hg, and Pb) with graphene and carbon nanotubes by evaluating van der Waals $C_3$ coefficients using well-known Lifshitz theory. The dispersion coefficients are expressed in terms of reflection coefficients of graphene and carbon nanotubes which are calculated within the framework of Dirac model. In addition, accurate values of dynamic dipole polarizabilities at imaginary frequencies of considered ions and atoms which are vital, have been calculated using relativistic methods. The comparisons of our calculated static dipole polarizabilities for the considered elements with the values reported in the literature are also presented. The dispersion interactions of the considered heavy elements with the graphene and carbon nanotubes of different radii in a wide range of separation distances have been studied. The results have also been analysed with another subtle variable, i.e., gap parameter of graphene wall. The interaction coefficients obtained for both the materials, i.e., for graphene and carbon nanotubes are mutually compared and it is found that graphene can be said as preferable material for adsorption of these toxic heavy elements.