Lanthanum(III)hydroxide Nanoparticles and Polyethyleneimine-Functionalized Graphene Quantum Dot Nanocomposites in Photosensitive Silicon Heterojunctions

Lanthanides are largely used in optoelectronics as dopants to enhance the physical and optical properties of semiconducting devices. In this study, lanthanum(III)hydroxide nanoparticles (La(OH)3NPs) are used as a dopant of polyethylenimine (PEI)-functionalized nitrogen (N)-doped graphene quantum dots (PEI-NGQDs). The La(OH)3NPs-dopedPEI-NGQDs nanocomposites are prepared from La(NO)3 in a single step by a green novel method and are characterized by Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Deposited over an n-type Si wafer, the La(OH)3NPs-dopedPEI-NGQDs nanocomposites form Schottky diodes. The I-V characteristics and the photoresponse of the diodes are investigated as a function of the illumination intensity in the range 0-110 mW cm-2 and at room temperature. It is found that the rectification ratio and ideality factor of the diode decrease, while the Schottky barrier and series resistance increase with the enhancing illuminations. As a photodetector, the La(OH)3NPs-dopedPEI-NGQDs/n-Si heterojunction exhibits an appreciable responsivity of 3.9 × 10-3 AW-1 under 22 mW cm-2 at -0.3 V bias and a maximum detectivity of 8.7 × 108 Jones under 22 mW cm-2 at -0.5 V. This study introduces the green synthesis and presents the structural, electrical, and optoelectronic properties of La(OH)3NPs-dopedPEI-NGQDs, demonstrating that these nanocomposites can be promising for optoelectronic applications.

Hydrothermal control, characterization, growth mechanism, and photoluminescence properties of highly crystalline 1D Eu(OH)3 nanostructures

Six types of 1D Eu(OH)₃ nanostructures with typical morphologies, including short hexagonal prism, long hexagonal prism, coiling rod, short rod, long rod, and nanobunch, were synthesized via the hydrothermal route using EuCl₃ and NaOH as raw materials. The morphologies, sizes, structures, and compositions of the as-prepared products were characterized by scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, X-ray diffraction, and Fourier transform infrared spectroscopy. The effects of different reaction conditions on the morphology and size of the products were also investigated, and the relevant growth mechanism was assessed. Results showed that the geometric features of Eu(OH)₃ are affected by the precursor pH and reaction time and temperature; among these factors, precursor pH played a key role in controlling the morphologies of the resulting Eu(OH)₃ nanostructures. The fluorescence properties of the six Eu(OH)₃ nanostructures were analyzed, and typical photoluminescence emission peaks due to the ⁵D₀–⁷F_J (J = 1–4) transition of Eu³⁺ were noted. Moreover, the intensity of the emission peak of the products at 616 nm was slightly weaker than that at 592 nm. This finding reflects the high site symmetry of Eu³⁺ in the Eu(OH)₃ nanostructures.

Six types of 1D Eu(OH)₃ nanostructures with typical morphologies, including short hexagonal prism, long hexagonal prism, coiling rod, short rod, long rod, and nanobunch, were synthesized via the hydrothermal route using EuCl₃ and NaOH as materials.

Green fabrication of lanthanide-doped hydroxide-based phosphors: Y(OH)3:Eu3+ nanoparticles for white light generation

Phosphors can serve as color conversion layers to generate white light with varying optical features, including color rendering index (CRI), high correlated color temperature (CCT), and luminous efficacy. However, they are typically produced under harsh synthesis conditions such as high temperature, high pressure, and/or by employing a large amount of solvent. In this work, a facile, water-based, rapid method has been proposed to fabricate lanthanide-doped hydroxide-based phosphors. In this sense, sub-micrometer-sized Y(OH)₃:Eu³⁺ particles (as red phosphor) were synthesized in water at ambient conditions in ≤60 min reaction time. The doping ratio was controlled from 2.5-20 mol %. Additionally, first principle calculations were performed on Y(OH)₃:Eu³⁺ to understand the preferable doping scenario and its optoelectronic properties. As an application, these fabricated red phosphors were integrated into a PDMS/YAG:Ce³⁺ composite and used to generate white light. The resulting white light showed a remarkable improvement (≈24%) in terms of luminous efficiency, a slight reduction of CCT (from 3900 to 3600 K), and an unchanged CRI (≈60) as the amount of Y(OH)₃:Eu³⁺ was increased.

Development of 3-methoxyaniline sensor probe based on thin Ag2O@La2O3 nanosheets for environmental safety

An electrochemical sensor based on glassy carbon electrode modified by Ag₂O@La₂O₃ nanosheets with 5% ethanolic nafion as conducting binder was developed for the selective and ultra-sensitive determination of 3-methoxyanaline in the presence of other interfering toxic chemicals in aqueous system by electrochemical approach for the first time.

Enhanced removal of phosphate and nitrate ions from aqueous media using nanosized lanthanum hydrous doped on magnetic graphene nanocomposite

A novel nanocomposite adsorbent based on nanosized lanthanum hydroxide doped onto magnetic reduced graphene oxide (MG@La) was synthesized and used for removal of phosphate and nitrate ions from river and sewage media. The composition, surface properties and morphology of the as prepared adsorbent were studied using Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The influence of main parameters on the efficiency of removal process including adsorbent dosage, salt addition, solution pH, contact time, and concentration of the analytes were thoroughly investigated. The validity of the experimental process was checked by the adsorption isotherm and adsorption kinetics models. The obtained data were well fitted to Langmuir isotherm and pseudo-second-order kinetic models. The developed adsorbent showed high adsorption capacities of 116.28 mg g^-1 and 138.88 mg g^-1 for phosphate and nitrate ions, respectively. Additionally, Langmuir isotherm and free energy were suggested monolayer pattern and physisorption mechanism for adsorption process, respectively. Finally, the field application of newly synthesized MG@La provided high removal efficiencies (74%-90%) for phosphate and nitrate ions in real river and sewage water samples.

Experimental observation of spatially resolved photo-luminescence intensity distribution in dual mode upconverting nanorod bundles

A novel method for demonstration of photoluminescence intensity distribution in upconverting nanorod bundles using confocal microscopy is reported. Herein, a strategy for the synthesis of highly luminescent dual mode upconverting/downshift Y_1.94O₃:Ho³⁺_0.02/Yb³⁺_0.04 nanorod bundles by a facile hydrothermal route has been introduced. These luminescent nanorod bundles exhibit strong green emission at 549 nm upon excitations at 449 nm and 980 nm with quantum efficiencies of ~6.3% and ~1.1%, respectively. The TEM/HRTEM results confirm that these bundles are composed of several individual nanorods with diameter of ~100 nm and length in the range of 1–3 μm. Furthermore, two dimensional spatially resolved photoluminescence intensity distribution study has been carried out using confocal photoluminescence microscope throughout the nanorod bundles. This study provides a new direction for the potential use of such emerging dual mode nanorod bundles as photon sources for next generation flat panel optical display devices, bio-medical applications, luminescent security ink and enhanced energy harvesting in photovoltaic applications.

Emerging La2O2CN2 matrix with controllable 3D morphology for photoluminescence applications

Shape-controlled La₂O₂CN₂ microstructures are synthesized and are used as hosts for doping with various RE³⁺ to realize different colored emissions.

Synthesis, crystal structure, and luminescence properties of a new europium silicate

A new europium silicate, NaEuSi₃O₇(OH)₂ (denoted as 1), was synthesized under high-temperature and high-pressure conditions, and structurally characterized by single-crystal and powder X-ray diffraction (XRD) analyses.