Liquid-assisted, etching-free, mechanical peeling of 2D materials

Mechanical peeling is a well-known route to transfer a single piece of two-dimensional (2D) materials from one substrate to another one, yet heavily relies on trial and error methods. In this work, we propose a liquid-assisted, etching-free, mechanical peeling technique of 2D materials and systemically conduct a theoretical study of the peeling mechanics for various 2D materials and substrates in a liquid environment. The surface wettability of 2D materials and substrates and surface tension of liquids have been incorporated into the peeling theory to predict the peel-off force. The theoretical model shows that the peel-off force can be significantly affected by liquid solvents in comparison with that in dry conditions. Moreover, our analysis reveals that the mechanical peeling-induced selective interface delamination in multilayered 2D materials can be achieved by employing a liquid environment. These theoretical results and demonstrations have been extensively confirmed by comprehensive molecular dynamics simulations and good agreement is obtained between them. The present work in theory provides a new approach of peeling 2D materials from substrates and can also be extended for peeling thin films and membranes.