Versatile Polymer-Free Graphene Transfer Method and Applications.

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Chemical vapor deposition (CVD) is crucial for synthesizing high-quality monolayer graphene.
• Transferring CVD graphene to target substrates often involves polymers, leading to contamination and performance issues.
• Developing polymer-free transfer methods is essential for realizing graphene's full potential.

Purpose of the Study:

• To introduce a new, polymer-free method for transferring CVD-grown monolayer graphene.
• To demonstrate the transfer of graphene to various substrates, including complex 3D architectures.
• To explore the utility of transferred graphene in applications like conductive AFM and TEM.

Main Methods:

• Utilized an organic/aqueous biphasic system (hexane/aqueous ammonium persulfate) for copper etching.
• Employed an Si/SiO2 substrate at a secondary hexane/water interface to remove etching byproducts.
• Transferred graphene to arbitrary substrates, including atomic force microscopy (AFM) tips and transmission electron microscopy (TEM) grids.

Main Results:

• Achieved conformal graphene coating on AFM tips, enabling conductive AFM imaging.
• Created large-area, electron-transparent graphene/TEM grids for high-resolution imaging.
• Demonstrated the use of these substrates as working electrodes for electrochemistry and wetting studies.
• Utilized scanning electrochemical cell microscopy to compare electrochemical and wetting behaviors on freestanding vs. copper-supported graphene.

Conclusions:

• The developed biphasic transfer method effectively transfers CVD monolayer graphene without polymer contamination.
• This technique allows for the creation of advanced graphene-based substrates and devices for nanoscale imaging and electrochemical analysis.
• The method broadens the applicability of graphene in fields requiring high-performance, contamination-free interfaces.