Self-cleaning by harnessing wrinkles in two-dimensional layered crystals

Abstract

Two-dimensional (2D) layered crystals are prone to bending and folding owing to their ultra-low bending stiffness. Folds are traditionally viewed as defects that degrade the material performance. Here, we demonstrate that folds and cohesive forces in 2D layered crystals like graphene and MoS₂ can be exploited to collect and clean up interlayer impurities, wherein multiple separated impurities agglomerate into a single, large cluster. We combine classical molecular dynamics simulations and an analytical model to elucidate the competing roles of membrane bending and impurity-membrane cohesive energies in the self-cleaning process. Our findings shed light on the mechanisms by which the forces that are present in 2D layered crystals can positively impact, through the possibility of intrinsic cleaning and defect engineering, the synthesis of van der Waals homo- and heterostructures with improved reliability and functionalities.