Room temperature phosphorescence sensor for Hg2+ based on Mn-doped ZnS quantum dots

Area of Science:

• Materials Science
• Environmental Science
• Analytical Chemistry

Background:

• Mercury pollution poses significant risks to human health and ecosystems.
• Developing sensitive and selective sensors for mercury ion (Hg2+) detection is crucial for environmental monitoring.
• Quantum dots (QDs) offer unique photoluminescent properties for sensing applications.

Purpose of the Study:

• To synthesize L-cysteine-capped manganese-doped zinc sulfide quantum dots (QDs).
• To utilize these QDs for the room temperature phosphorescence detection of mercury ions (Hg2+).
• To investigate the sensing mechanism and performance of the developed QD sensor.

Main Methods:

• Synthesis of L-cysteine-capped Mn-doped ZnS QDs.
• Room temperature phosphorescence spectroscopy for Hg2+ detection.
• Analysis of UV-vis absorption and Rayleigh scattering spectra to study the quenching mechanism.

Main Results:

• The phosphorescence of Mn-doped ZnS QDs was selectively quenched by Hg2+ ions.
• A good linear correlation was observed between phosphorescence intensity and Hg2+ concentration from 2.0 x 10(-8) to 4.5 x 10(-6) mol/L.
• A low detection limit of 3.8 x 10(-9) mol/L was achieved.
• The long phosphorescence lifetime of the QDs minimizes interference from background autofluorescence and scattering.

Conclusions:

• L-cysteine-capped Mn-doped ZnS QDs are effective for sensitive and selective detection of Hg2+.
• The developed sensor shows potential for practical application in monitoring mercury pollution in real samples.
• The long phosphorescence lifetime enhances the reliability of the detection method.