One‐Step Exfoliation Method for Plasmonic Activation of Large‐Area 2D Crystals

Abstract

Advanced exfoliation techniques are crucial for exploring the intrinsic properties and applications of 2D materials. Though the recently discovered Au‐enhanced exfoliation technique provides an effective strategy for the preparation of large‐scale 2D crystals, the high cost of gold hinders this method from being widely adopted in industrial applications. In addition, direct Au contact could significantly quench photoluminescence (PL) emission in 2D semiconductors. It is therefore crucial to find alternative metals that can replace gold to achieve efficient exfoliation of 2D materials. Here, the authors present a one‐step Ag‐assisted method that can efficiently exfoliate many large‐area 2D monolayers, where the yield ratio is comparable to Au‐enhanced exfoliation method. Differing from Au film, however, the surface roughness of as‐prepared Ag films on SiO2/Si substrate is much higher, which facilitates the generation of surface plasmons resulting from the nanostructures formed on the rough Ag surface. More interestingly, the strong coupling between 2D semiconductor crystals (e.g., MoS2, MoSe2) and Ag film leads to a unique PL enhancement that has not been observed in other mechanical exfoliation techniques, which can be mainly attributed to enhanced light‐matter interaction as a result of extended propagation of surface plasmonic polariton (SPP). This work provides a lower‐cost and universal Ag‐assisted exfoliation method, while at the same time offering enhanced SPP‐matter interactions.

In Situ Exfoliation Method of Large‐Area 2D Materials

“…Meeting condition (1) in air or inside glove box environment is problematic because of the requirement for exfoliation to be performed immediately after metallic surface evaporation, and because most ex vacuo surfaces will quickly undergo chemistry or adsorption of impurities, even in a glovebox. Recent work has shown that the Ag substrate exhibits a similar exfoliation yield as Au, [ 76 ] but the observed efficiency declines rapidly within ≈10 s due to surface oxidation. This effect limits the possible choice of substrate to relatively non‐reactive Au or Ag and makes the exfoliation technically challenging.…”

Recent Progress in Two-Dimensional Material Exfoliation Technology and Enlightenment for Geological Sciences

“…42 Recently, a one-step Ag-assisted method has been developed by Huang et al that efficiently exfoliates many large-area 2D monolayers. 43 The yield ratio of this method is comparable to that of the Au-film-assisted exfoliation method. However, it is worth noting that the surface roughness of Ag films on SiO 2 /Si substrates is higher compared to Au films.…”

“…as an intermediary layer. 32,43 Finding a cheaper intermediary material that can achieve high-quality and largearea exfoliation is an area that requires further exploration.…”

“…Currently, the exfoliation of large-area 2D semiconductors still mainly relies on noble metals (gold, silver, etc.) as an intermediary layer. , Finding a cheaper intermediary material that can achieve high-quality and large-area exfoliation is an area that requires further exploration.…”

Advances in the understanding of the structure–performance relationships of 2D material catalysts based on electron microscopy

“…They are usually prepared by mechanically assisted exfoliation, ion intercalation/sonification-assisted liquid exfoliation, and chemical vapor deposition (CVD). [28][29][30][31][32] In contrast, nonlayered materials typically include ultrathin nanosheets of metal and metal oxides, are usually known as 3D bulk crystals connected by strong chemical bonds. However, they are limited in one direction to form 2D nanosheet structures during crystallization.…”