Gd3+ and Sm3+ Ions Modulated Visible-Light-Emitting ZnSe:Mn2+ Nanocrystals for Detection of Pb2+ and Hg2+

High Resolution Image Download MS PowerPoint Slide Luminescent semiconductor nanocrystals (NCs) with strong visible emission are highly desirable for the sensitive detection of heavy metal ions at trace levels. Herein, the study focuses on enhanceing Mn 2+ ion emission achieved by incorporating trivalent lanthenide (Ln 3+ ) ions, i.e ., Sm 3+ and Gd 3+ ions, at the Zn sites in a ZnSe lattice. This enhancement was confirmed by integrated photoluminescence (PL) and X-ray emission optical luminescence (XEOL), supported by quantitative X-ray absorption fine structure (XAFS) analyses. The observed increase in the visible emission was attributed to efficient energy transfer from Sm 3+ /Gd 3+ to Mn 2+ centers in ZnSe NCs. The luminescent NCs are subsequently employed as nanosensors for detecting Pb 2+ and Hg 2+ ions, exhibiting marked quenching upon exposure. The calculated limits of detection (LoDs) for Pb 2+ (2.51 μM) and Hg 2+ (6.63 μM) demonstrate greater sensitivity toward Pb 2+ as compared to Hg 2+ . The system is selective across a range of interfering ions (i.e., Ag 1+, Co 2+, Ni 2+, Cd 2+, Gd 3+, Tm 3+, Yb 3+, and Er 3+ ) having different oxidation states when present concurrently. Furthermore, lifetime decay measurements, combined with Stern–Volmer analysis, indicate that quenching likely occurs through both static and dynamic mechanisms. These results highlight the potential of colloidal ZnSe:Mn 2+,Sm 3+ NCs as effective platforms for the sensitive and selective detection of toxic metal ions and have the potential to be employed for environmental monitoring applications.