Simple preparation of graphene quantum dots with controllable surface states from graphite

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Graphite is an abundant and cost-effective precursor for carbon-based nanomaterials.
• Graphene quantum dots (GQDs) possess unique optical and electronic properties derived from graphene.
• Controlling the surface chemistry of GQDs is crucial for tailoring their functionality.

Purpose of the Study:

• To develop a facile and green method for producing graphene quantum dots (GQDs) from graphite.
• To investigate the influence of high-power sonication on the GQD formation mechanism during pulsed laser ablation (PLA).
• To achieve selective synthesis of GQDs and graphene oxide quantum dots (GOQDs) by controlling sonication.

Main Methods:

• Utilizing pulsed laser ablation (PLA) in liquid on graphite flakes.
• Employing high-power sonication to assist or omit during the PLA process.
• Characterizing the synthesized nanomaterials using structural, chemical, and optical techniques.

Main Results:

• High-power sonication during PLA promotes a homogeneous dispersion, leading to GQDs via a laser fragmentation in liquid (LFL) mechanism.
• Absence of sonication results in the formation of graphene oxide quantum dots (GOQDs) with oxygen-rich functional groups.
• Synthesized GQDs retain the intrinsic properties of pristine graphene, while GOQDs exhibit different luminescence.
• Selective production of GQDs or GOQDs is achieved by toggling sonication during PLA.

Conclusions:

• The modified PLA process offers a simple and effective route for selective GQD and GOQD synthesis.
• Sonication plays a critical role in determining the formation mechanism and surface functionalization of quantum dots from graphite.
• This method provides a versatile platform for designing functional carbon nanomaterials for various applications.