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ZnO Micro- and Nanostructures Obtained by Thermal Oxidation: Microstructure, Morphogenesis, Optical, and Photoluminescence Properties
摘要： ZnO micro- and nanostructures were obtained through thermal oxidation of Zn powders at high temperature under air atmosphere. A detailed study of the microstructure, morphology, optical, and photoluminescence properties of the generated products at different stages of thermal oxidation is presented. It was found that the exposure time has a strong influence on the resulting morphology. The morphogenesis of the different ZnO structures is discussed, and experimental parameters for fabricating ZnO tetrapods, hollow, core-shell, elongated, or rounded structures by thermal oxidation method are proposed on the basis on the obtained results. Notoriously, the crystal lattice of the ZnO structures has negligible residual strain, although, the density of point defects increases when the thermal treatment is extended; as consequence, their visible luminescence upon UV excitation enhances.
关键词： growth mechanism,ZnO structures,thermal oxidation,physical properties
更新于2025-09-23 15:23:52
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Fabrication and photocatalytic performance evaluation of hydrodynamic erosion–resistant nano-TiO2–silicone resin composite films
摘要： Herein, we present the preparation of nano-TiO2–silicone resin composite films by double liquid phase spray deposition. The films exhibit better adhesion stability and photocatalytic activity under a hydrodynamic erosion condition than conventional nano-TiO2 composite films. The TiO2 layer morphology and effective TiO2 coverage ratio (CR) were affected by the initial curing time (ICT) of the silicone resin, e.g., the increase in an ICT from 10 to 40 min resulted in a CR change from 79.1 to 98.7%. The surface morphology evolution of composite films was studied under a hydrodynamic erosion period of 4 weeks. Obtained results allowed the 4-week evolution to be divided into four stages (pitting, crack pregnant, banded stripping, and surface stripping periods), additionally revealed that the CR of all samples was remained above 65%. The photocatalytic activity of composite films before and after 4-week hydrodynamic erosion was evaluated by rhodamine B degradation experiments. The 4-week erosion only led to the decrease of the photodegradation efficiencies by less than 40% in all cases. Thus, the fabricated TiO2–silicone composite films demonstrated excellent durability and photocatalytic activity under the conditions of long-term hydrodynamic erosion, allowing one to conclude that this work paves the way to the fabrication of next-generation photocatalytic materials for industrial applications.
关键词： Photocatalysis,Film formation mechanism,Silicone resin,Photodegradation,Hydrodynamic erosion resistance,Nano-TiO2
更新于2025-09-23 15:23:52
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Facile synthesis of three-dimensional ZnO hierarchical microspheres composed of well-ordered nanorods by hydrothermal method
摘要： Three-dimensional (3D) ZnO hierarchical microspheres composed of well-ordered nanorods were synthesized by a facile one-step hydrothermal method without any surfactants. The effects of reaction conditions including reaction temperature, reaction time on the microstructure of hierarchical microspheres were investigated. The results demonstrated that the reaction conditions played an important role in the morphology of 3D ZnO hierarchical microspheres. A three-stage reaction mechanism of 3D ZnO hierarchical microspheres was proposed. Firstly, Zn2+ reacts with OH- and NH4+ to produce nanoparticles. Then the nanoparticles are self-assembled into nucleis. Finally is the formation and growth of the hierarchical structure on the nuclear surface. When the as-synthesized ZnO were used as the anode of the dye sensitization solar cells (DSSCs), the 3D ZnO hierarchical microspheres composed of well-ordered nanorods exhibits the best photoelectric properties, which was attributed to the increased surface area and advantageous electronic transmission path.
关键词： photoelectric properties,Hierarchical microspheres,conditions,mechanism
更新于2025-09-23 15:23:52
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Atomic-scale simulations of ideal strength and deformation mechanism in β-SiC under H/He irradiation
摘要： We ?rstly investigated the mechanical responses of β-SiC to the tensile and shear strains under H/He irradiation using density functional theory, with a speci?c focus on the atomistic mechanism of deformation and fracture. The results revealed that the e?ect of introducing H/He on ideal strengths of tension and shear is limited, due to the strong sp3 bonds of Si-C. However, somehow large disparity in failure was discovered after introducing H/He. Under the tension, all Si-C bonds along the tensile direction are synchronously broken, causing cubic-to-graphitic transformation in the perfect β-SiC, in contrast to the asynchronous breakage of Si-C bonds in the H/He-doping systems. Under the shear, H- and He-doping systems display individual cleavage-like modes of lattice instability, respectively, whereas structural transformation by re-bonding new Si-C bonds is responsible for the failure in the perfect β-SiC. The cleavage-like modes were discussed, combining a detailed analysis of electronic structure. The mechanical response to H/He irradiation distinguishes β-SiC from conventional metals presently applied in nuclear industry. The study may provide a clue for new design strategy of irradiation-tolerant materials for energy applications.
关键词： Ideal strength,H/He irradiation,Deformation mechanism,β-SiC ceramic
更新于2025-09-23 15:23:52
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Dehydrogenation-driven to synthesize high-performance Lu2Si4N6C:Ce3+- a broad green-emitting phosphor for full-spectrum?lighting
摘要： Green phosphor Lu2Si4N6C:Ce3+ (LSNC:Ce3+) shows an ideal feasibility to the near ultraviolet LED (n-UV LED) for “Full-Spectrum Lighting” (FSL). However, it is complex to synthesize pure Lu2Si4N6C phase. Herein, we prepared LSNC:Ce3+ via a novel dehydrogenation-driven high temperature solid-state reaction method, which distinctly optimized the morphology, and then significantly enhanced the photoluminescent performance of LSNC:Ce3+. The improving mechanism ascribed to the stepwise dehydrogenation of LuH3 which was beneficial to further shear LuH3 particles. The LSNC:Ce3+ phosphor obtained by the optimized process exhibits excellent thermal stability, and its external quantum efficiency is 57.3 %. Interestingly, the intensities of excitation peaks decrease at 375 nm while it increases at 425 nm gradually with the Ce3+ concentration. It is reasonably ascribed to the different ability of photo-ionization in different 5d levels. Finally, the constructed w-LED with the titled phosphor exhibits a well-distributed warm white light with high color rendering index (Ra = 96.6, R9 = 96, R12 = 82). It indicates that the LSNC:Ce3+ gives assistance to compensation for the “spectrum chasm” in blue-green region, as well as contributes to the improvement of Ra and R9, that is beneficial for full-spectrum lighting.
关键词： Carbonitride,n-UV LED,Reaction mechanism,Full-Spectrum,Green phosphor Lu2Si4N6C:Ce3+
更新于2025-09-23 15:23:52
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The red persistent luminescence of (Sr,Ca)AlSiN3:Eu2+ and mechanism different to SrAl2O4:Eu2+,Dy3+
摘要： (Sr,Ca)AlSiN3:Eu2+ phosphors have been widely used in phosphor-converted white light emitting diodes. Herein, we reported the strong red persistent luminescence in (Sr,Ca)AlSiN3:Eu2+ under UV light excitation. The Sr0.8Ca0.2AlSiN3:0.15% Eu2+ shows the strongest red persistent luminescence with a peak emission wavelength at ~628 nm and a persistent time of ~9600 s at the 0.32 mcd/m2 threshold value. A new persistent luminescence mechanism, which is different to that of SrAl2O4:Eu2+,Dy3+, was proposed by comparing the thermoluminescence excitation spectrum (TLES) and the photoluminescence excitation spectrum (PLES) of Sr0.8Ca0.2AlSiN3:0.15% Eu2+. The electrons are directly excited from 4f ground states to the conduction band or from valence band to conduction band in (Sr,Ca)AlSiN3:Eu2+; while, in SrAl2O4:Eu2+,Dy3+, they are first excited to 5d level and then stimulated thermal process to the conduction band. The effect of Eu2+ concentration on red persistent luminescence in (Sr,Ca)AlSiN3:Eu2+ were discussed. The proposed mechanism of persistent luminescence can help us to design and find new persistent luminescence materials.
关键词： Persistent luminescence,SrAl2O4:Eu,Dy,Red emission,(Sr,Ca)AlSiN3:Eu,Persistent luminescence mechanism
更新于2025-09-23 15:23:52
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Crystal structure, optical and electrical properties of metal-halide compound [C7H16N2][ZnCl4]
摘要： A new organic–inorganic hybrid compound [C7H16N2][ZnCl4] was synthesized by hydrothermal method and characterized by single-crystal X-ray diffraction, IR and Raman spectroscopy, optical absorption, differential scanning calorimetry and dielectric measurements. Single crystal diffraction results showed that [C7H16N2][ZnCl4] crystallizes in the monoclinic system, space group P21/c at room temperature. In the molecular arrangement, the tetrachlorozincate anions are connected to organic cations through N-H...Cl hydrogen bonds. The Raman and IR analyses confirm the presence of the organic groups and the anionic entities. UV–Visible absorption spectrum revealed the energy of the optical band gap. DSC measurements indicated that [C7H16N2][ZnCl4] undergoes three sequential phase transitions at 287, 338 and 356 K. The dielectric study proved the ferroelectric properties below the 338K and indicates their classical character for this compound. The analysis of Nyquist plots revealed the contribution of the bulk mechanism and the grain boundaries.
关键词： Phase transitions,Hybrid material,Crystal structure,Optical absorption,Ferroelectric properties,Conduction mechanism
更新于2025-09-23 15:23:52
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ZnO rod decorated with Ag nanoparticles for enhanced photocatalytic degradation of methylene blue
摘要： Silver-zinc oxide nanocomposite (Ag-ZnO nanocomposite) were synthesised with different concentrations of Ag doped to the ZnO for enhance photocatalytic degradation of methylene blue. The structures, morphologies, and optical properties of synthesised nanocomposites were characterized by UV-Visible spectroscopy (UV-vis) scanning electron microscopy (SEM), X-ray diffraction (XRD), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FRIR), and photoluminescence spectroscopy (PL). The average size of the synthesized Ag nanoparticles was around 40 nm and ZnO nanorod were 2 μm in length and 200 nm in width. The morphological characterization revealed that Ag nanoparticles were well doped with the ZnO rod surface. The performance and stability of the nanocomposites for the photocatalytic degradation of methylene blue under ultraviolet (UV) light irradiation were evaluated. The overall results suggested that, 6% of Ag nanoparticles achieved better degradation than compare to the other concentrations and bare ZnO. This work provides a simple and effective route to prepare Ag-ZnO nanocomposite for effective degradation of methylene blue. Therefore, Ag-ZnO nanocomposite can be regarded as a potential candidate for application in the treatment of waste water.
关键词： Methylene blue,Ag-ZnO nanocomposites,Mechanism,Photocatalysis
更新于2025-09-23 15:23:52
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Fabrication of magnetically separable NiFe2O4/Bi24O31Br10 nanocomposites and excellent photocatalytic performance under visible light irradiation
摘要： Novel multifunctional NiFe2O4/Bi24O31Br10 nanocomposites were synthesized by a thermal decomposition process and hydrothermal route. The structures, morphologies, as well as the magnetic, optical and visible-light photocatalytic properties of the as-prepared nanocomposites were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, vibrating sample magnetometer (VSM) and UV–visible diffuse reflectance spectroscopy (DRS). The experimental results reveal that the NiFe2O4/Bi24O31Br10 composites exhibit an enhanced photocatalytic activity for photo-degradation of crystal violet (CV) under visible light irradiation. Among the prepared samples, the 20% NiFe2O4/Bi24O31Br10 nanocomposite displays the best photocatalytic activity, which is mainly ascribed to the efficient separation of photo-induced electron-hole pairs. Hydroxyl (?OH) radicals and holes are confirmed to be the dominant active species in the NiFe2O4/Bi24O31Br10 photocatalytic system. Furthermore, due to their excellent ferromagnetism and stability, NiFe2O4/Bi24O31Br10 nanocomposites can be easily separated from contaminant solution by using a magnet, implying that they have promising application in treatment of various dyestuff wastewaters on a large scale.
关键词： Mechanism,NiFe2O4,Bi24O31Br10,Photocatalytic,Nanocomposites
更新于2025-09-23 15:23:52
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40.3: Invisibility Mechanism Research of Metal Bridge in Capacitive Touch Panel and Optimal Design Solution
摘要： This paper shows deep analysis and research for the invisibility mechanism in large size capacitive touch panel. Invisibility of metal bridge is influenced by LCD module and touch panel together, main factors should be studied together. Experimental verification results show that: (1) when the PPI of LCD module is lower, the area of the LCD Dot occupied by the metal bridge is smaller, then the invisibility effect will be better. (2) The bigger pitch of touch panel pattern will result in the lower density of metal bridge. (3) The invisibility of touch panel also can be improved by the angle change of metal bridge especially when the bridge has intersection angle with LCD RGB dot from 15° to 45°. (4) The width of hammer in metal bridge plays a good role for invisibility, and the improvement effect will not be obvious in a certain width. (5) Whether the direction of the metal bridge and the RGB unit is vertical or parallel almost has no impact on the invisibility. These conclusions can provide references for the follow up product development.
关键词： Capacitive Touch Panel,Invisibility Mechanism,Metal Bridge
更新于2025-09-23 15:23:52