First-principles calculations of graphene nanoribbons in gaseous environments: Structural and electronic properties

TL;DR

This study uses density functional theory to analyze the stability and electronic properties of graphene nanoribbons with various edge passivations in gaseous environments, revealing oxygen saturation as particularly stable and metallic.

Contribution

It provides a systematic first-principles investigation of how different atmospheric molecules affect the stability and electronic structure of graphene nanoribbons.

Findings

Oxygen-saturated zig-zag edges are highly stable under atmospheric conditions.

Oxygen passivation induces localized metallic states on the edges.

Vibrational spectra differ notably between hydrogen and oxygen passivated ribbons.

Abstract

The stability of graphene nanoribbons in the presence of typical atmospheric molecules is systematically investigated by means of density functional theory. We calculate the edge formation free energy of five different edge configurations passivated by H, H$_2$, O, O$_2$, N$_2$, CO, CO$_2$, and H$_2$O, respectively. In addition to the well known hydrogen passivated armchair and zig-zag edges, we find the zig-zag edge saturated by oxygen atoms to be particularly stable under atmospheric conditions. Saturation by oxygen leads to the formation of metallic states strictly localized on the oxygen atoms. Finally, the vibrational spectrum of the hydrogen and oxygen passivated ribbons are calculated and compared.