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

Author(s)

Gul, Iram ; Khan, Zahid U. ; Galani, Sammra ; Huda, Subul ; Khan, Latif U. ; Juwhari, Hassan K. ; Hyder, Ali ; Brito, Hermi F. ; Zaheer, Muhammad ; Khan, Muhammad Abdullah

• Document type: Journal article
• Source: ACS APPLIED OPTICAL MATERIALS; v. N/A, p. 11-pg., 2025-08-19.

Abstract

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 Mn2+ ion emission achieved by incorporating trivalent lanthenide (Ln3+) ions, i.e., Sm3+ and Gd3+ 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 Sm3+/Gd3+ to Mn2+ centers in ZnSe NCs. The luminescent NCs are subsequently employed as nanosensors for detecting Pb2+ and Hg2+ ions, exhibiting marked quenching upon exposure. The calculated limits of detection (LoDs) for Pb2+ (2.51 mu M) and Hg2+ (6.63 mu M) demonstrate greater sensitivity toward Pb2+ as compared to Hg2+. The system is selective across a range of interfering ions (i.e., Ag1+, Co2+, Ni2+, Cd2+, Gd3+, Tm3+, Yb3+, and Er3+) 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:Mn2+,Sm3+ 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. (AU)

• FAPESP's process: 21/00356-6 - Multifunctional fluorescence quantum dots as amplifiers for 1O2 generation and synergistic enhanced photodynamic therapy
• Grantee: Zahid Ullah Khan
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 21/08111-2 - Development of rare earth based light converters: luminescent markers, optical sensors, and amplifiers
• Grantee: Hermi Felinto de Brito
• Support Opportunities: Research Projects - Thematic Grants