Dissociative Adsorption of Molecules on Graphene and Silicene

TL;DR

This study investigates how molecules interact with vacancy defects in graphene and silicene, revealing that certain molecules can dissociate at defect sites, altering electronic and magnetic properties, which enables potential functionalization of these materials.

Contribution

It provides new insights into the dissociation mechanisms of molecules at defect sites in graphene and silicene, highlighting their potential for material functionalization.

Findings

H₂, O₂, and CO dissociate at defect sites, modifying properties.

H₂O and OH dissociation are hindered by high energy barriers.

Defect engineering enables selective molecule dissociation and pinning.

Abstract

We study the interaction of H$_2$, O$_2$, CO, H$_2$O and OH molecules with the vacancy defects of graphene and silicene. Atoms around the bare vacancy reconstruct and specific chemically active sites are created. While H$_2$, O$_2$ and CO remain intact on both pristine graphene and silicene, these molecules can dissociate when they are placed at the close proximity of these chemically active sites and nucleate centers for the hydrogenation and oxygenation. Saturation of the dangling bonds at the defect sites by constituent atoms of dissociated molecules gives rise to significant modification of electronic and magnetic properties. We analyzed the mechanism of the dissociation and revealed a concerted action of surrounding host atoms together with dissociated molecules to lower the energy barrier needed for dissociation. The dissociations of H$_2$O and OH are hindered by high energy barriers. Our study suggests that graphene and silicene can be functionalized by creating meshes of single vacancy, where specific molecules can dissociate, while some other molecules can be pinned.