Can Adsorption on Graphene be Used for Isotopic Enrichment? A DFT Perspective.

Mateusz Pokora,Piotr Paneth

doi:10.3390/molecules23112981

Abstract

We have explored the theoretical applicability of adsorption on graphene for the isotopic enrichment of aromatic compounds. Our results indicate that for nonpolar molecules, like benzene, the model compound used in these studies shows a reasonable isotopic fractionation that is obtained only for the deuterated species. For heavier elements, isotopic enrichment might be possible with more polar compounds, e.g., nitro- or chloro-substituted aromatics. For benzene, it is also not possible to use isotopic fractionation to differentiate between different orientations of the adsorbed molecule over the graphene surface. Our results also allowed for the identification of theory levels and computational procedures that can be used for the reliable prediction of the isotope effects on adsorption on graphene. In particular, the use of partial Hessian is an attractive approach that yields acceptable values at an enormous increase of speed.

Highlights

Properties of newly developed carbon materials, like fullerenes, nanotubes, and graphene, are getting increasing attention due to scientific curiosity and due to possible practical applications [1].With its high conductivity both electrical [2] and thermal [3], graphene has been studied as a possible material for transistors and other electrical appliances [4]
In the quest for finding the economic theory level for reliable calculations of the isotope effects on adsorption, we have studied the performance of the QM/QM calculations within the ONIOM
For the studied model compound, both the differentiation of the adsorbed molecule orientations over the graphene surface using isotopic fractionation, as well as the application of the adsorption on graphene for isotopic enrichment, seem realistic only for the deuterated species due to the small values and small differences of the carbon isotope effects associated with this process

Summary

Introduction

Properties of newly developed carbon materials, like fullerenes, nanotubes, and graphene, are getting increasing attention due to scientific curiosity and due to possible practical applications [1].With its high conductivity both electrical [2] and thermal [3], graphene has been studied as a possible material for transistors and other electrical appliances [4]. Graphene was examined as a potential sorbent of organic pollutants, such as dyes [5], aromatic compounds [6,7,8], and heavy metals [5,9] from water and aqueous solutions. It was considered for the capturing of biologically active substances [8,10] as well as a potential “scavenger” of greenhouse gases like CO2 [11,12,13,14], CH4 , or N2 [12]. It has been reported that the adsorption of small molecules like H2 O, H2 , O2 , CO, NO, and NO2 leads to the doping of graphene [15] which makes it a useful method for creating potential graphene-based electronic components

Methods

Results

Conclusion