Large-scale synthesis and functionalization of hexagonal boron nitride nanosheets

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Hexagonal boron nitride (hBN) is a layered material with unique properties.
• Exfoliation of hBN into few-layer sheets is challenging.
• Controlled functionalization is key to enhancing hBN properties and processability.

Purpose of the Study:

• To develop a simple and inexpensive method for functionalizing and exfoliating hexagonal boron nitride (hBN).
• To investigate the stability and characteristics of the exfoliated hBN nanosheets.
• To confirm the functionalization and structural integrity of the resulting nanomaterial.

Main Methods:

• Functionalization of hBN using a mixture of phosphoric and sulfuric acids.
• Exfoliation of functionalized hBN into monolayer to few-layer sheets.
• Characterization using transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).

Main Results:

• A simple and cost-effective method for hBN functionalization and exfoliation was established.
• Exfoliated hBN nanosheets demonstrated stability in various common solvents (ethanol, acetone, water, IPA).
• Sulfur functionalization was confirmed via XPS, with B 1s peak deconvolution revealing B-O and B-S bonding. Crystalline nature and an optically active defect at 320 nm were observed.

Conclusions:

• The acid-assisted functionalization provides an efficient route to stable, exfoliated hBN nanosheets.
• Sulfur functionalization is crucial for the observed stability and unique optical properties of the exfoliated hBN.
• This method offers a scalable approach for producing high-quality hBN nanomaterials for diverse applications.