A Greener Approach towards Making Highly Luminescent Ln3+-Doped NaYF4Nanoparticles with Ligand-Assisted Phase Control

Large-Scale Mechanochemical Synthesis of Cesium Lanthanide Chloride for Radioluminescence

Cesium lanthanide chloride (Cs3LnCl6), a recently developed class of lanthanide-based zero-dimensional metal halides, has garnered a significant amount of interest because of its potential applications in scintillators, light-emitting diodes, and photodetectors. Although cesium lanthanide chloride demonstrates exceptional scintillator properties, conventional synthesis methods involving solid-state and solution-phase techniques are complex and limited on the reaction scale. This study presents a facile mechanochemical synthesis method for producing Cs3CeCl6, Cs3TbCl6, and Cs3EuCl6 metal halides on a 5 g scale. These materials exhibit intense blue-violet, green, and red emissions upon ultraviolet excitation, with high photoluminescence quantum yields ranging from 54% to 93%. Furthermore, Cs3CeCl6, Cs3TbCl6, and Cs3EuCl6 metal halides exhibit intense radioluminescence spanning from the ultraviolet to the visible region. This research shows the potential of the scalable mechanochemical synthesis of lanthanide-based metal halides for the advancement of luminescent materials for scintillators.

Recent Progresses in NIR-II Luminescent Bio/Chemo Sensors Based on Lanthanide Nanocrystals

Fluorescent bio/chemosensors are widely used in the field of biological research and medical diagnosis, with the advantages of non-invasiveness, high sensitivity, and good selectivity. In particular, luminescent bio/chemosensors, based on lanthanide nanocrystals (LnNCs) with a second near-infrared (NIR-II) emission, have attracted much attention, owing to greater penetration depth, aside from the merits of narrow emission band, abundant emission lines, and long lifetimes. In this review, NIR-II LnNCs-based bio/chemo sensors are summarized from the perspectives of the mechanisms of NIR-II luminescence, synthesis method of LnNCs, strategy of luminescence enhancement, sensing mechanism, and targeted bio/chemo category. Finally, the problems that exist in present LnNCs-based bio/chemosensors are discussed, and the future development trend is prospected.

Design of Lanthanide-Doped Colloidal Nanocrystals: Applications as Phosphors, Sensors, and Photocatalysts

The unique optical characteristics of lanthanides (Ln³⁺) such as high color purity, long excited-state lifetimes, less perturbation of excited states by the crystal field environment, and the easy spectral conversion of wavelengths through upconversion and downconversion processes have caught the attention of many scientists in the recent past. To broaden the scope of using these properties, it is important to make suitable Ln³⁺-doped materials, particularly in colloidal forms. In this feature article, we discuss the different synthesis strategies for making Ln³⁺-doped nanoparticles in colloidal forms, particularly ways of functionalizing hydrophobic surfaces to hydrophilic surfaces to enhance their dispersibility and luminescence in aqueous media. We have enumerated the various strategies and sensitizers utilized to increase the luminescence of the nanoparticles. Furthermore, the use of these colloidal nanoparticle systems in sensing application by the appropriate selection of capping ligands has been discussed. In addition, we have shown how the energy transfer efficiency from Ce³⁺ to Ln³⁺ ions can be utilized for the detection of toxic metal ions and small molecules. Finally, we discuss examples where the spectral conversion ability of these materials has been used in photocatalysis and solar cell applications.

Energy transfer from Er to Nd ions by the thermal effect and promotion of the photocatalysis of the NaYF4:Yb,Er,Nd/W18O49 heterostructure

The NaYF4:Yb,Er/W18O49 heterostructure is an excellent photocatalyst that can promote H2 evolution by hydrolyzing BH3NH3 under near-infrared (NIR) light irradiation. At the same time, the photothermal effect can be produced in photocatalytic reactions, which will cause the luminescence efficiency and photocatalytic activity to decrease. Determining how to take advantage of that photothermal effect becomes a major problem. Moreover, the energy transfer (ET) process from Er ions to Nd ions in NaYF4 co-doped with Yb/Er/Nd ions (NaYF4:Yb,Er,Nd) occurred at high temperature. Herein, the NaYF4:Yb,Er,Nd/W18O49 quasi-core-shell heterostructure was designed to achieve better H2 production capacity; this heterostructure exhibits a 1.5-fold enhancement of photocatalytic activity for H2 evolution as compared with the NaYF4:Yb,Er/W18O49 heterostructure. This study provides a new way to explore the catalytic activities in the NIR field for application in the development of a sustainable energy source.