Effect of Ultrahigh Stiffness of Defective Graphene from Atomistic Point of View

TL;DR

This study reveals that monovacancy defects can significantly increase the stiffness of graphene, contrasting with typical degradation effects of point defects in bulk materials, based on atomistic simulations and experimental data.

Contribution

It demonstrates that monovacancy defects uniquely enhance graphene's stiffness, providing new insights into defect-induced mechanical properties of low-dimensional materials.

Findings

Monovacancies can stiffen graphene at low concentrations.

Other point defects cause stiffness degradation.

Simulation results align with experimental observations.

Abstract

Well-known effect of mechanical stiffness degradation under the influence of point defects in macroscopic solids can be controversially reversed in the case of low-dimensional materials. Using atomistic simulation, we showed here that a single-layered graphene film can be sufficiently stiffened by monovacancy defects at a tiny concentration. Our results correspond well with recent experimental data and suggest that the effect of mechanical stiffness augmentation is mainly originated from specific bonds distribution in the surrounded monovacancy defects regions. We showed that such unusual mechanical response is the feature of presence of specifically monovacancies, whereas other types of point defects such as divacancy, 555-777 and Stone-Wales defects, lead to the ordinary degradation of the graphene mechanical stiffness.