Electrochemical delamination assisted transfer of molecular nanosheets

Abstract

Delamination and transfer of two-dimensional (2D) materials from their synthesis substrates onto target substrates is an important task for their implementation in both fundamental and applied research. To this end, the electrochemical delamination based transfer has been successfully applied to a variety of inorganic 2D materials grown on conductive substrates. However, this promising method has not yet been demonstrated for organic 2D materials, which have recently gained significant importance in the 2D materials family. Here, we present a transfer method of molecular nanosheets covalently bonded to metal substrates based on electrochemical delamination, which involves the cleavage of an Au–S bond and hydrogen evolution. We demonstrate a successful transfer of different types of carbon nanomembranes (CNMs) – about 1 nm thick molecular nanosheets – synthesized from aromatic thiol-based self-assembled monolayers on various polycrystalline gold substrates, onto new target substrates such as SiO₂/Si wafers and transmission electron microscopy grids. We analyze the subsequent nanofabrication steps, and chemical and structural characteristics of the transferred supported and suspended CNMs by X-ray photoelectron spectroscopy (XPS), optical microscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The XPS analysis enables us to reveal the chemical mechanisms during the delamination process, whereas the complementary microscopy measurements confirm a high structural integrity of the transferred molecular nanosheets. We expect that the developed methodology can be applied to a broad variety of organic 2D materials synthesized on conductive substrates.