Revealing the Effects of Pore Size and Geometry on the Mechanical Properties of Graphene Nanopore Using the Atomistic Finite Element Method

Abstract

Graphene nanopore has been extensively employed in nanoscale sensing devices due to its outstanding properties. The understanding of its mechanical properties at nanoscale is crucial for sensing improvement. In this work, the mechanical properties of graphene nanopore are thus investigated using the atomistic finite element method. Four graphene models with different pore shapes (circle (CR), horizontal rectangle (RH), vertical rectangle (RV) and square (SQ)) in sub-5nm size, which could be successfully fabricated experimentally, have been studied here. The force normal to a pore rim is applied to mimic the impact force due to a fluid flow. As expected, the strength of nanoholed graphene is pore size dependent. Increasing pore size results in the reduction in its strength. Comparing between different pore shapes with comparable sizes, the order of pore strength is $$\hbox {CR}>\hbox {RH}>\hbox {RV}>\hbox {SQ}$$ . In addition, two different corner structures (V-like or zigzag and C-like or armchair corners) are observed, where the V-like structure causes higher tensile stress. Besides, we find that the highest tensile stress is produced at the corner in all cases. This finding suggests the corners as an origin of pore fracture. The results of RH and RV highlight the impact of a direction of pore orientation on mechanical properties. Aligning a long side of a pore along the zigzag direction gains more tensile stress, while aligning on an armchair side causes a deflection. Not only the pore geometry and size, but also the pore orientation is crucial for defining the mechanical properties of nanopores.