Effect of Topo Ratio in the Formation of In-Situ Hydrophobic Core–Shell Nanoparticle of Europium Oxide

Activated trivalent lanthanide (Eu³⁺) inorganic nanoparticles were regarded as the best possible alternative to conventional molecular bio probes and highly appropriate for use as sensitive time-resolved PL bio probes for bio-detection. Because of their strong photochemical stability, unique crisp emission lines, and high quantum efficiencies, rare-earth-based nanomaterials are the most utilized luminous materials. Furthermore, the coupling of vibrational modes of other molecules over the surface of the rare earth nanoparticles and other surface imperfections causes emission quenching. One potential strategy for preventing or minimizing these effects is to use a passivation agent that interacts with the surface of the nanoparticles. This study focuses on the passivation of tri-octyl phosphine oxide (TOPO) with europium oxide to form in-situ hydrophobic TOPO shell europium oxide nanoparticles for improving the physical, chemical, and optical properties of Eu³⁺ ions. The Eu:TOPO ratio of the nanoparticle was optimized for effective photoluminescence and particle crystallinity by photoluminescence spectroscopy and XRD analysis. The controlled size and shape of the material were analyzed by FESEM and EDS studies. Further, the XPS, Raman spectroscopy, and ¹H-NMR studies examined the incorporation of TOPO with europium oxide nanoparticles. The optical properties of the TOPO-capped europium oxide nanoparticles were evaluated by UV-Vis DRS and time-resolved fluorescence spectroscopy. Thus, this study is based on the efficiency of varied TOPO capping ratios with synthesized europium oxide nanoparticles in generating a size-regulated, highly stable, and effective luminous material with a higher quantum yield than europium oxide.