Novel worm-like Ag/ZnO core–shell heterostructural composites were fabricated using a two-step chemical method. As-prepared silver nanowires were soaked in a solution of zinc acetate and triethanolamine to form worm-like Ag/ZnO core–shell composites under ultrasonic irradiation. Samples were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, and UV–vis spectrophotometer. The results show that the core–shell composites are composed of single-crystal Ag nanowires serving as the core, on which dense ZnO particles grow as the shell. The surface plasmon absorption band of Ag/ZnO composites is distinctly broadened and red shifted to monometallic Ag nanowires. The PL intensity of Ag/ZnO heterostructural composites varies and has the minimum intensity for the sample prepared with Ag of 2.8 atom %. Moreover, photocatalytic tests show that the Ag/ZnO composites exhibit higher photocatalytic activity compared to pure ZnO particles.
In this Letter, we report a novel NaLaMgWO6:Mn4+ double-perovskite phosphor. Under the excitation at 342 nm, this phosphor showed a high-efficiency far-red emission at approximately 700 nm with internal quantum efficiency of up to 60%. Moreover, it exhibited a high thermal stability; the emission intensity at 423 k was approximately 57% of that at room temperature. Finally, a prototype light-emitting diode (LED) device was fabricated using the combination of a NaLaMgWO6:Mn4+ far-red-emitting phosphor and 365-nm LED chip.
Highly efficient Ce3+ → Tb3+ energy transfer induced bright narrowband green emissions from Ca2YZr2(AlO4)3:Ce3+,Tb3+ garnet phosphors, which showed great potential for application in warm-white LEDs with high color rendering index.
In this work, Ce3+-activated Ba3Lu2B6O15 (BLBO) blue-emitting phosphors were prepared, and their photoluminescence properties were studied. It was found that these phosphors can be excited over a broad excitation band range from 300 nm to 430 nm and generated a blue emission band in the 400-550 nm range with a maximum peak at 443 nm. The full width at half maximum of the blue emission band was about 68 nm. The optimal doping concentration of Ce3+ ions was determined to be 3 mol. %, and the BLBO:0.03Ce3+ phosphors possessed an internal quantum efficiency as high as 71%. Finally, by coating the phosphors with a blend of commercial CaAlSiN3:Eu2+ red-emitting phosphors, (Ba,Sr)2SiO4:Eu2+ green-emitting phosphors, and BLBO:0.03Ce3+ blue-emitting phosphors on a 380 nm ultraviolet light-emitting diode (LED) chip, a white LED device with a color-rendering index of ∼94 and correlated color temperature of 4952 K was obtained.
The flexible thermoelectric (TE) generator has emerged as a superior alternative to traditional batteries for powering wearable electronic devices, as it can efficiently convert skin heat into electricity without any safety concerns. MXene, a highly researched two-dimensional material, is known for its exceptional flexibility, hydrophilicity, metallic conductivity, and processability, among other properties, making it a versatile material for a wide range of applications, including supercapacitors, electromagnetic shielding, and sensors. However, the low intrinsic Seebeck coefficient of MXene due to its metallic conducting nature poses a significant challenge to its TE application. Therefore, improving the Seebeck coefficient remains a primary concern. In this regard, a flexible MXene/organics/TiS2 misfit film was synthesized in this work through organic intercalation, exfoliation, and re-assembly techniques. The absolute value of Seebeck coefficient of the misfit film was significantly enhanced to 44.8 μV K–1, which is five times higher than that of the original MXene film. This enhancement is attributed primarily to the weighted effect of the Seebeck coefficient and possibly to energy-filtering effects at the heterogeneous interfaces. Additionally, the power factor of the misfit film was considerably improved to 77.2 μW m–1 K–2, which is 18 times higher than that of the original MXene film. The maximum output power of the TE device constructed of the misfit film was 95 nW at a temperature difference of 40 K, resulting in a power density of 1.18 W m–2, demonstrating the significant potential of this technology for driving low-energy consumption wearable electronics.
Two-dimensional (2D) materials with outstanding electronic transport properties are rigid against bending because of strong in-plane covalent bonding and intrinsically flexible because of the lack of out-of-plane constraint and thus are considered to be promising for flexible thermoelectrics (TEs). As a typical 2D material, MXene, however, exhibited a restricted TE performance because the termination groups and guest molecules in MXene nanosheets introduced by acid etching and reassembly deteriorate intra/interflake conduction. This work realized increases in both the carrier concentration and intra/interflake mobility by the construction of a MXene nanosheet/organic superlattice (SL) and composition engineering, attributed to electron injection, intercoupling strengthening, and defect reduction at the nanosheet edges. An electrical conductivity increased by 5 times, to 2.7 × 105 S m–1, led to power factors of up to ∼33 μW m–1 K–2, which is above the state-of-the-art for similar materials, almost by a factor of 10. A TE module comprising four SL film legs could yield 58.6 nW power at a temperature gradient of 50 K. Additionally, both the annealed film and the corresponding module exhibited excellent reproducibility and stability. Our results provide a strategy to tailor the TE performance of 2D-material films through SL construction and composition engineering.
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