Doping-Guided Control of Lead-Sensitized Terbium Emission in Zinc Sulfide Nanoparticles: Implications for Lead Ion Sensing in Aqueous Media

Pb2+ codoping enhances the Tb3+ emission in trivalent terbium-doped zinc sulfide [Zn­(Tb)­S] nanoparticles (NPs). The Tb3+-Pb2+ spatial proximity and a favorable codopant electronic energy level alignment contribute toward this emission brightening. This work tests the performance of the Tb3+ emission in the Zn­(TbPb)S and Zn­(Tb)­S/Pb NPs, where the dopants within parentheses and after slashes indicate their synthetic and postsynthetic doping, respectively. When screened against steady-state and time-resolved photoluminescence, photoelectron spectroscopy, zeta potential, and infrared absorption of surface capping ligands, the Zn­(TbPb)S NPs emerge as a superior sensitizer to generate Tb3+ emission. A core dominant Tb3+-Pb2+ interaction in Zn­(TbPb)S NPs prompts a stronger Tb3+ emission when compared to the surface dominant Tb3+-Pb2+ interaction in Zn­(Tb)­S/Pb NPs. This doping strategy guided the NP design principle to control lanthanide emission, which expands the palette of lanthanide-based NP luminophores for practical applications. The Pb2+‑sensitized Tb3+ emission brightening in the ZnS NPs in the precation exchange reaction conditions can find applications in Pb2+ sensing, cellular imaging, and light emitting diodes (LEDs).