Multi-functional ratiometric detection based on dual-emitting N-doped carbon dots

Area of Science:

• Materials Science
• Analytical Chemistry
• Environmental Science

Background:

• Ratiometric fluorescence probes enhance detection accuracy for environmental monitoring.
• Carbon dots (CDs) offer tunable optical properties for sensing applications.

Purpose of the Study:

• To synthesize and characterize novel dual-emitting nitrogen-doped carbon dots (N-CDs).
• To develop a multi-functional ratiometric probe for simultaneous detection of environmental parameters.

Main Methods:

• Solvothermal synthesis of N-doped carbon dots (N-CDs) from citric acid and urea in DMF.
• Characterization of N-CDs' optical properties, including dual emission and solvatochromism.
• Evaluation of N-CDs as ratiometric probes for metal ions (Fe3+, Cu2+, Ag+), water content, pH, and temperature.

Main Results:

• Achieved pure white light emission (CIE coordinates of (0.33, 0.33)) from N-CDs in water.
• Demonstrated selective detection of Fe3+, Cu2+, and Ag+ ions with ppm-level LOD.
• Observed a green emission in organic solvents, quenching with increasing polarity, enabling water content detection (LOD 0.003%-0.3%).
• Exhibited pH sensitivity (4.0-7.0) and temperature dependence (15-70 °C).

Conclusions:

• A versatile, multi-functional ratiometric probe based on N-CDs was successfully developed.
• The probe enables simultaneous and sensitive detection of metal ions, water content, pH, and temperature.
• Future research should address the excitation wavelength limitation (330 nm) for broader applications.