Microplasma Band Structure Engineering in Graphene Quantum Dots for Sensitive and Wide-Range pH Sensing

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Nanomaterials offer promising pH sensing capabilities for various scientific fields.
• Challenges remain in developing rapid, sensitive, stable, biocompatible, and cost-effective nanomaterial-based pH sensors.

Purpose of the Study:

• To rationally design nitrogen-doped graphene quantum dot (NGQD)-based pH sensors with enhanced properties.
• To achieve rapid, sensitive, quantitative, stable, and cost-effective pH detection using nanotechnology.

Main Methods:

• Microplasma-enabled band-structure engineering to boost NGQD pH sensing properties.
• Synthesis of emission-tunable NGQDs from chitosan biomass precursor under ambient conditions.
• Advanced spectroscopy and density functional theory (DFT) calculations to analyze sensing mechanisms.

Main Results:

• Functionality-tuned NGQDs exhibit enriched -OH groups, enabling rapid, label-free, and ionic-stable pH sensing.
• Achieved a wide pH sensing range from 1.8 to 13.6 with a stable and large Stokes shift.
• Microplasma synthesis is scalable, cost-effective, and produces stable NGQD dispersions suitable for numerous detections.

Conclusions:

• Microplasma engineering of NGQDs provides a generic and effective approach for advanced pH sensing.
• This method opens new avenues for nanographene-based materials in sensing, catalysis, optoelectronics, and biomedical applications.