Modeling of gas adsorption on graphene nanoribbons

TL;DR

This paper develops a theoretical model combining ab initio calculations and tight-binding approximation to study gas molecule adsorption on graphene nanoribbons, considering edge states and adsorption effects on electronic properties.

Contribution

It introduces a novel approach integrating ab initio data with tight-binding models to analyze gas adsorption on AGNRs, including edge state effects and adsorption site uniformity.

Findings

CO and NO adsorption create localized states near the band gap

CO$_2$ acts as an acceptor, NH$_3$ as a donor

Model results agree with density-functional theory at low concentrations

Abstract

We present a theory to study gas molecules adsorption on armchair graphene nanoribbons (AGNRs) by applying the results of \emph{ab} \emph{initio} calculations to the single-band tight-binding approximation. In addition, the effect of edge states on the electronic properties of AGNR is included in the calculations. Under the assumption that the gas molecules adsorb on the ribbon sites with uniform probability distribution, the applicability of the method is examined for finite concentrations of adsorption of several simple gas molecules (CO, NO, CO$_2$, NH$_3$) on 10-AGNR. We show that the states contributed by the adsorbed CO and NO molecules are quite localized near the center of original band gap and suggest that the charge transport in such systems cannot be enhanced considerably, while CO$_2$ and NH$_3$ molecules adsorption acts as acceptor and donor, respectively. The results of this theory at low gas concentration are in good agreement with those obtained by density-functional theory calculations.