Surfactant-free single-layer graphene in water

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Achieving bulk quantities of single-layer graphene (SLG) dispersed in water has been a significant challenge.
• A reliable in situ diagnostic tool for identifying solubilized graphene has been lacking.

Purpose of the Study:

• To develop a method for producing stable, bulk aqueous dispersions of single-layer graphene.
• To establish an in situ diagnostic technique for verifying the presence and characteristics of solubilized graphene.

Main Methods:

• Homogeneous stable dispersions of single-layer graphene (SLG) were produced by mixing graphenide solutions in tetrahydrofuran with degassed water.
• The organic solvent was evaporated, and the resulting aqueous dispersions were analyzed using in situ Raman spectroscopy.
• Transmission electron microscopy (TEM) and atomic force microscopy (AFM) were employed on deposits to confirm the single-layer nature of the graphene.

Main Results:

• Stable, additive-free single-layer graphene (SLG) dispersions in water were successfully obtained.
• In situ Raman spectroscopy confirmed the characteristic spectral signatures of SLG in the aqueous dispersions.
• Microscopy techniques verified the single-layer morphology of the graphene.
• The dispersions achieved a high graphene surface area of 400 m² L⁻¹.
• Films fabricated from these dispersions demonstrated electrical conductivity up to 32 kS m⁻¹.

Conclusions:

• A novel and effective method for producing bulk quantities of stable single-layer graphene (SLG) in water has been demonstrated.
• The developed technique provides a valuable tool for in situ characterization of graphene in aqueous media.
• The resulting graphene dispersions hold promise for various applications requiring conductive and high-surface-area materials.