Site-dependent hydrogenation on graphdiyne

TL;DR

This study investigates how hydrogen atoms attach to and modify the structure of graphdiyne membranes using reactive molecular dynamics, revealing complex hydrogenation patterns distinct from graphene.

Contribution

It provides the first detailed analysis of hydrogenation mechanisms on graphdiyne, highlighting differences from graphene and potential for band gap tuning.

Findings

Hydrogen binds at different rates to various atoms in graphdiyne.

Hydrogenation patterns evolve complexly over time.

No formation of correlated hydrogenated domains as in graphene.

Abstract

Graphene is one of the most important materials in science today due to its unique and remarkable electronic, thermal and mechanical properties. However in its pristine state, graphene is a gapless semiconductor, what limits its use in transistor electronics. In part due to the revolution created by graphene in materials science, there is a renewed interest in other possible graphene-like two-dimensional structures. Examples of these structures are graphynes and graphdiynes, which are two-dimensional structures, composed of carbon atoms in sp2 and sp-hybridized states. Graphdiynes (benzenoid rings connecting two acetylenic groups) were recently synthesized and some of them are intrinsically nonzero gap systems. These systems can be easily hydrogenated and the relative level of hydrogenation can be used to tune the band gap values. We have investigated, using fully reactive molecular dynamics (ReaxFF), the structural and dynamics aspects of the hydrogenation mechanisms of graphdiyne membranes. Our results showed that the hydrogen bindings have different atom incorporation rates and that the hydrogenation patterns change in time in a very complex way. The formation of correlated domains reported to hydrogenated graphene is no longer observed in graphdiyne cases.