Fabrication of multifunctional 3D-flower-shaped NaTb(MoO₄)₂:Dy³⁺@Phen and NaTb(WO₄)₂:Dy³⁺@Phen nanoparticle materials for efficacious luminescence sensing of Fe²⁺ ions and photocatalytic degradation of rhodamine B in an aqueous medium

The existence of industrial pollutants, especially metal ions and organic dyes, in water bodies has put at risk human health and the global environment, which makes it necessary to design dual-functional nanoparticles that not only have excellent luminescence sensing ability but also possess simultaneous photodegradation activity against harmful pollutants. Herein, we have synthesized NaTb(MoO4)(2):Dy3+@Phen and NaTb(WO4)(2):Dy3+@Phen (Phen = 1,10-phenanthroline) nanoparticles using a hydrothermal synthetic method and evaluated their functional activity for the photoluminescent sensing of Fe2+ ions and photocatalytic degradation of rhodamine B (RhB) in an aqueous medium. The physicochemical characterization of the synthesized nanoparticles was undertaken using various techniques. A photoluminescent study of NaTb(MoO4)(2):Dy3+@Phen showed that it is extremely sensitive and displays selective chemical sensing towards Fe2+ ions in an aqueous medium. The PL emission band at 545 nm displayed notable quenching on adding different concentrations of Fe2+ ions to a colloidal solution of the prepared nanoparticles. Moreover, NaTb(MoO4)(2):Dy3+@Phen possessed a limit of detection (LOD) of 0.56 ppm and a Stern-Volmer (K-SV) constant of 6.35 x 10(3) M-1 for Fe2+ ions, which establish the high selectivity and sensitivity of the synthesized nanoparticles for Fe2+ ions. Additionally, the NaTb(WO4)(2):Dy3+@Phen nanoparticles showed noteworthy photocatalytic activity toward the degradation of RhB in an aqueous medium. The results obtained from UV-Vis spectroscopy clearly indicate that NaTb(WO4)(2):Dy3+@Phen (E-g = 3.10 eV) nanoparticles could act as a better photocatalyst than NaTb(MoO4)(2):Dy3+@Phen (E-g = 3.72 eV) nanoparticles. The degradation efficiency of NaTb(WO4)(2):Dy3+@Phen toward RhB is observed to be about 97.2% within 50 min under UV light and it also shows excellent stability even after four repeated catalytic runs. In general, this work provides a practicable approach for the instantaneous detection of Fe2+ ions and the photocatalytic degradation of RhB in an aqueous medium using NaTb(MoO4)(2):Dy3+@Phen and NaTb(WO4)(2):Dy3+@Phen as potential dual-functional nanomaterials.