An efficient down conversion luminescencent probe based on a NaGdF 4 :Eu 3+ /Ce 3+ nanophosphor for chemical sensing of heavy metal ions (Cd 2+ , Pb 2+ and Cr 3+ ) in waste water

• Published in: New journal of chemistry Vol. 44; no. 3; pp. 1009 - 1020
• Main Authors: Tashi, Lobzang, Kumar, Manesh, ul Nisa, Zaib, Nelofar, Nargis, Sheikh, Haq Nawaz
• Format: Journal Article
• Language: English
• Published: 21.01.2020
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C9NJ04889H

Heavy metal ions (such as Cd 2+ , Pb 2+ , Cr 3+ etc. ) present in wastewater effluents pose a great challenge in developing and underdeveloped countries. Herein, we report a facile hydrothermal synthesis and characterization of hexagonal Eu 3+ doped and Eu 3+ /Ce 3+ co-doped NaGdF 4 nanophosphors. Importantly, we demonstrate the NaGdF 4 :Eu 3+ /Ce 3+ nanophosphor as an efficient photoluminescent probe for chemical sensing of heavy metal ions, namely Cd 2+ , Pb 2+ and Cr 3+ , present mainly in industrial effluents. The structural characterization of the as fabricated nanophosphors has been appropriately performed by powder X-ray diffraction study (PXRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR) and energy-dispersive X-ray spectrometry (EDS). Vibrating sample magnetometry (VSM), photoluminescence (PL) spectra and phosphorescence lifetime measurements of the as synthesized nanophosphors have been used to explore their potential applications. It is observed that Eu 3+ /Ce 3+ codoped nanophosphors show relatively better luminescence intensities as compared to NaGdF 4 :Eu 3+ . The energy transfer process (through sensitizer Ce 3+ to mediator Gd 3+ and finally to activator Eu 3+ ) has been validated in an elegant way. The observed data for chemical sensing of three heavy metal ions (Cd 2+ , Pb 2+ and Cr 3+ ) show good Stern–Volmer fitting.