Remarkable enhancement in failure stress and strain of penta-graphene via chemical functionalization

Penta-graphene (PG), a newly proposed two-dimensional material composed entirely of carbon pentagons, is believed to possess much lower failure stress and strain than those of graphene. An open question is whether and how these properties can be enhanced. Herein using molecular dynamics simulations, we examine the deformation and failure processes of PG functionalized with different functional groups. We reveal that complete chemical functionalization leads to remarkable increases in the failure stress and strain of PG by up to 86.6% and 82.4%, respectively. The underlying reason for this enhancement is that the buckled pentagonal rings in pristine and partially functionalized PGs can easily transform into planar polygon rings under stretching; in contrast, complete functionalization of PG strongly stabilizes its structure and prevents such transformation, thereby significantly increasing the failure stress and strain. Our findings suggest a possible route to enhance the mechanical properties of PG for potential applications in nanocomposites and nanodevices.