Covalent functionalization of strained graphene

TL;DR

This study uses first-principles modeling to explore how mechanical strain affects the chemical activity and functionalization of graphene with various groups, revealing strain-dependent stability and magnetic properties.

Contribution

It provides new insights into how strain influences chemisorption energetics and magnetic stability in graphene, aiding the design of strain-engineered graphene devices.

Findings

Negative strain favors single adatom chemisorption over pairs.

Compressed graphene buckles spontaneously after chemisorption.

Oxidation becomes exothermic under strain, depending on strain direction.

Abstract

Enhancement of the chemical activity of graphene is evidenced by first-principles modelling of chemisorption of the hydrogen, fluorine, oxygen and hydroxyl groups on strained graphene. For the case of negative strain or compression, chemisorption of the single hydrogen, fluorine or hydroxyl group is energetically more favourable than those of their pairs on different sublattices. This behaviour stabilizes the magnetism caused by the chemisorption being against its destruction by the pair formations. Initially flat, compressed graphene is shown to buckle spontaneously right after chemisorption of single adatoms. Unlike hydrogenation or fluorination, the oxidation process turns from the endothermic to exothermic for all types of the strain and depends on the direction of applied strains. Such properties will be useful in designing graphene devices utilizing functionalization as well as mechanical strains.