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This study reports on the synthesis and characterization of a series of lithium gallate (LiGa5O8) phosphors doped with varying concentrations of Eu3+ ions. X-ray powder diffraction analysis confirmed the synthesis of the cubic phase of LiGa5O8, with additional peaks corresponding to Eu2O3 at higher dopant concentrations. Rietveld refinement confirmed the formation of a spinel-structured host with a space group of P4322. Ultraviolet-visible spectroscopy was used to analyze the absorption properties of the phosphor material and estimate the bandgap for all synthesized samples, which ranged from 4.75 to 4.95 eV, indicating the formation of a wide bandgap semiconductor stable at room temperature. Morphological and compositional analysis, along with surface mapping, were conducted using field emission scanning electron microscopy, energy dispersive electron spectroscopy, and time-of-flight secondary ion mass spectroscopy. X-ray photoelectron spectroscopy provided insights into the crystal structure and revealed the presence of oxygen vacancies and some other crystal defects. Photoluminescent properties were examined through photoluminescence excitation and emission spectra for all doped samples. Notably, samples doped with 6 and 7 mol% Eu3+ displayed a prominent excitation peak at 247 nm corresponding to the presence of Eu2O3, while the remaining samples exhibited characteristic Eu3+ excitation. Lifetime measurements for both excitation wavelengths showed decay times in the millisecond range. The emission color of all samples resided within the red region of the electromagnetic spectrum, boasting remarkable color purity. The results suggest that this material has potential as a red light-emitting component for LED applications. [ABSTRACT FROM AUTHOR]

MnO2 is widely utilized as a vulcanizing agent for polysulfide (PS) sealing; however, it is difficult to flexibly adjust the vulcanizing process while keeping costs low. Herein, we successfully prepared α-MnO2, γ-MnO2 and δ-MnO2, as characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping and X-ray photoelectron spectroscopy, and found for the first time that the photogenerated carriers on MnO2 can trigger the free radical attack of –SH under visible light, leading to rapid, efficient and controllable PS sealing. Furthermore, the effect of different treatment conditions, crystalline form, and light power density on the curing rate was investigated. δ-MnO2 showed better PS sealing performance under irradiation of 1140 mW cm−2 than under natural light and dark conditions, and δ-MnO2 showed a higher curing rate than those of α-MnO2 and γ-MnO2. Moreover, the curing rate increased with an increase in the light power density. The induction time and curing rate can be flexibly controlled by adjusting the optical power density and turning the light on/off. Furthermore, the effect of illumination uniformity on rubber surface shape was investigated, and a sample with a flat surface was obtained under uniform illumination. In addition, two pathways of photocatalytic initiation and the traditional PS oxidation radical mechanism for polysulfide sealing over δ-MnO2via photo-assistance were proposed. This study details a novel, facile and general strategy to achieve rapid, efficient and controllable PS sealing in industrial settings. [ABSTRACT FROM AUTHOR]

MnO2 is widely utilized as a vulcanizing agent for polysulfide (PS) sealing; however, it is difficult to flexibly adjust the vulcanizing process while keeping costs low. Herein, we successfully prepared α-MnO2, γ-MnO2 and δ-MnO2, as characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping and X-ray photoelectron spectroscopy, and found for the first time that the photogenerated carriers on MnO2 can trigger the free radical attack of –SH under visible light, leading to rapid, efficient and controllable PS sealing. Furthermore, the effect of different treatment conditions, crystalline form, and light power density on the curing rate was investigated. δ-MnO2 showed better PS sealing performance under irradiation of 1140 mW cm−2 than under natural light and dark conditions, and δ-MnO2 showed a higher curing rate than those of α-MnO2 and γ-MnO2. Moreover, the curing rate increased with an increase in the light power density. The induction time and curing rate can be flexibly controlled by adjusting the optical power density and turning the light on/off. Furthermore, the effect of illumination uniformity on rubber surface shape was investigated, and a sample with a flat surface was obtained under uniform illumination. In addition, two pathways of photocatalytic initiation and the traditional PS oxidation radical mechanism for polysulfide sealing over δ-MnO2via photo-assistance were proposed. This study details a novel, facile and general strategy to achieve rapid, efficient and controllable PS sealing in industrial settings. [ABSTRACT FROM AUTHOR]

Nowadays, heterogeneous catalysts are preferable to homogeneous catalysts to get more socioeconomic assistance due to multiple recycling. In the current study, CuO/PVA nanocomposites were synthesized via the chemical reduction method, followed by ultra-sonication. The synthesized nanocomposites were confirmed using different characterization techniques, such as X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, dynamic light scattering, zeta potential, Fourier transform infrared spectroscopy, UV-Visible spectroscopy, and X-ray photoelectron spectroscopy. In order to verify their efficacy in the catalytic degradation, engineered CuO/PVA nanocomposites were used for the degradation of Rhodamine B dye in an aqueous medium. Finally, catalytic results exposed that copper oxide nanocatalyst showed an exceptional degradation, greater than 98% using a minimum catalyst dose of 150 μg within 75 s using optimized parameters for NaBH4 (125 μL) and Rhodamine B (0.01 M). To the best of our knowledge, this is the first study of Rhodamine B degradation by CuO/PVA nanocomposite as the catalyst. Certainly, the nanocatalyst presented here is more useful and realistic and hence can be suggested as an effective candidate for the successful degradation of complex dyes at the commercial level. [ABSTRACT FROM AUTHOR]