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Reversed Crystal Growth
摘要： In the last decade, a reversed growth route has been found in many crystal growth processes. In these systems, a single crystal does not develop from a single nucleus. The precursor molecules/ions or nanocrystallites aggregate into some large amorphous or polycrystalline particles. Multiple-nucleation on the surface of the amorphous particles or surface re-crystallization of the polycrystalline particles then takes place, forming a single crystal shell with a regular morphology. Finally, the crystallization extends from the surface to the core to form single crystals. This non-classical crystal growth route often results in some special morphologies, such as core-shell structures, hollow single crystals, sandwich structures, etc. This article gives a brief review of the research into reversed crystal growth and demonstrates that investigation of detailed mechanisms of crystal growth enables us to better understand the formation of many novel morphologies of the crystals. Some unsolved problems are also discussed.
关键词： nucleation,crystal growth,core-shell structure,crystal morphology,hollow crystal,electron microscopy
更新于2025-09-23 15:23:52
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Metal-Organic Frameworks Derived from Zero-Valent Metal Substrates: Mechanisms of Formation and Modulation of Properties
摘要： The replicative construction of metal–organic frameworks (MOFs) templated with solvent-insoluble solid substrates is of marked importance, as it allows for the assembly of 2D and 3D macro- and mesoscopic architectures with properties that are challenging to attain by the conventional solution-based synthesis approach. This work reports an in situ and direct construction of MOFs from zero-valent metal substrates via a green hydrothermal oxidation–MOF construction chemistry without the use of any additional metal source, chemical reagents, or acidification of solvent, and elucidates the zero-valent metal derived formation mechanisms of MOFs and their structure modulation to 1D nanofibers (NFs), 2D film, and 3D core–shell microstructures. Through modulation of the competing surface oxidation-dissolution and MOF crystallization kinetics, Al@MIL-53 core–shell microstructures and MIL-53 (Al) NFs are obtained that exhibit unique morphologies and marked properties superior to the conventional MIL-53 (Al) powders. The generality of zero-valent metal-templated synthesis of MOFs is demonstrated with formation of MIL-53 (Al), HKUST-1, and ZIF-7 polycrystalline films on Al, Cu, and Zn metal meshes, elucidating the significance of the approach utilizing solid metal substrate that can be easily processed into various shapes, architectures, and compositions.
关键词： MOF nanofibers,formation mechanism,core–shell structure,templated synthesis,metal–organic framework
更新于2025-09-23 15:22:29
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Design of Au@WO3 core?shell structured nanospheres for ppb-level NO2 sensing
摘要： As motivated by the driving force of the urgent demand for high-performance nitrogen dioxide (NO2) sensor, in this work, a novel structure of Au@WO3 core?shell nanospheres (CSNSs) was designed and successfully prepared for NO2 detection. The techniques of X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller measurement, and elemental mapping analysis were used for the characterizations of the obtained samples. The results demonstrated that Au nanoparticles with 25?50 nm in diameter were successfully encapsulated by WO3 shells with the thickness of 30?50 nm. The NO2 sensing performance of the Au@WO3 CSNSs as well as the pure WO3 nanospheres were systematically investigated. Compared with the pure WO3 nanospheres, Au@WO3 CNNSs exhibited overall enhanced NO2 sensing performances in terms of response, detection limit, and response/recovery times. At the optimal operating temperature of 100 °C, Au@WO3 CSNSs showed excellent NO2 selectivity and long-term stability. Notably, the excellent NO2 sensing performance of Au@WO3 CSNSs was slightly affected by humidity. The possible sensing mechanism of the enhanced NO2 sensing properties of the Au@WO3 CSNSs was discussed.
关键词： Au@WO3,Core?shell structure,Nanosphere,Gas sensor,NO2
更新于2025-09-23 15:21:21
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Core-shell Structured TiO2@In2O3 for Highly Active Visible-light Photocatalysis
摘要： Core-shell structured TiO2@In2O3 with high visible-light photocatalytic activity have been successfully fabricated by solvothermal method. The as-obtained products were characterized by field transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-visible diffuse reflectance spectra (UV-vis DRS). Structural characterizations demonstrated that the In2O3 layers were comprised of nanocrystallites ca. 14 nm in size and displayed rough surfaces. The UV-vis DRS data showed that In2O3 greatly expanded the visible light absorption band edge of TiO2. The results revealed that the obtained TiO2@In2O3 with core-shell structure showed enhancement of the visible-light photocatalytic activity to degrade methyl orange (MO) comparing with the pure TiO2 and In2O3 products.
关键词： TiO2@In2O3,Nanocomposites,Semiconductors,Core-shell structure
更新于2025-09-23 15:21:21
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Self-assembled CdS@BN core-shell photocatalysts for efficient visible-light-driven photocatalytic hydrogen evolution
摘要： CdS@BN NRs core-shell photocatalysts for hydrogen evolution were synthesized by a solvothermal and chemical adsorption method. CdS NRs coated by 5 wt% boron nitride (BN) shell exhibited remarkably visible-light photocatalytic hydrogen evolution activity of up to 30.68 mmol g?1 h?1, nearly 6.79 times higher than that of pure CdS NRs, and the apparent quantum efficiency at 420 nm was 7.5%. Transmission electron microscopy showed the CdS NRs were coated with a thin (~5 nm) BN layer, which together with the hydrogen evolution results proved the photocatalytic ability of CdS NRs was significantly improved. The hydrogen evolution rate of CdS NRs coated by 5 wt% BN remained at 91.4% after four cycles, indicating the photocorrosion of CdS NRs was effectively alleviated. Moreover, the large and close coaxial interfacial contact between the CdS core and the BN shell was beneficial to the separation and transfer of photogenerated electron-hole pairs.
关键词： Core-shell structure,Photocatalytic hydrogen evolution,CdS Nanorods,Boron nitride
更新于2025-09-23 15:21:01
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Organic Printed Core-Shell Heterostructure Arrays: A Universal Approach to All-Color Laser Display Panels
摘要： We demonstrate a universal approach for realizing dual-wavelength lasing in organic core-shell structured microlaser arrays, which show great promise in serving as all-color laser display panels. By alternately printing hydrophilic and hydrophobic laser dye solutions on preprocessed substrates, we successfully obtained precisely patterned core-shell heterostructure arrays. The spatially-separated core and shell independently function as optical resonators to support dual-wavelength tunable microlasers in each heterostructure. Such a general method enables to flexibly control the lasing wavelength of the core-shell microlasers across a wide spectral range by systematically designing the gain media. Using as-prepared microlaser arrays as display panels, we achieved full-color laser displays, representing an achievable color gamut much larger than that of standard RGB space. These results may provide new insights for design concepts and device construction for novel optoelectronic applications.
关键词： organic heterostructure,laser display,dual-wavelength laser,core-shell structure,laser array
更新于2025-09-23 15:21:01
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Direct Observation of Core-Shell Structures in Individual Lead Titanate Ferroelectric Nanostructures by Tip-Enhanced Refractive Index Mapping
摘要： Ferroelectrics undergo a size-driven phase transition at the nanoscale below which the spontaneous polarization, their defining property, irrevocably ceases. This threshold often referred to as the superparaelectric limit has tremendous technological relevance in an era of progressing integration. Just as the balance of short-range elastic and long-range electrostatic ordering in bulk, the critical size depends on temperature. Room-temperature tip-enhanced Raman spectroscopy (TERS) imaging of individual lead titanate (PbTiO3) nanoislands is reported with a spatial resolution of ≈3 nm. Monitoring the spectral shift of the gold-tip enhanced luminescence, which depends on the local refractive index, images grains composing the nanoislands. The wavelength of the enhanced luminescence shifts between the grains and their boundaries indicating the predicted core–shell structure of ferroelectric and paraelectric phase. The shear force configuration rules out the distance dependence of capacitive plasmonic coupling between tip and substrate as the origin of the observed shift. As the reported temperature-changes in nonresonant TERS do not account for noticeable thermal effects, the underlying, even though weak, tip-enhanced Raman spectrum of the grain core reflects PbTiO3 close to the ferroelectric-to-paraelectric phase transition which is primarily related to the finite size of the grains.
关键词： ferroelectric,tip-enhanced Raman spectroscopy,core–shell structure,local refractive index imaging,lead titanate
更新于2025-09-23 15:21:01
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Review on recent advances of core-shell structured lead halide perovskites quantum dots
摘要： Lead halide perovskites have shown great potential in photovoltaic and optoelectronic devices due to their high brightness, defect tolerance, tunable emission wavelength, high color purity and near-unity luminescence quantum yield. Conversely, lead halide perovskites (LHP) show poor stability, which received strong criticism despite other promising characteristics. The poor stability attracted much research resulting in various modifications to enhance the stability and photoluminescence quantum yield (PLQY). The review outlines the basic structural and optical properties along with the conventional method of LHP synthesis and its drawbacks. Simultaneously discusses about factors responsible for instability like crystal structure, moisture, solvent, light and temperature. The review exclusively focuses on the recent research on core-shell LHP modification strategy to improve the stability and PLQY and its application in LED devices.
关键词： photoluminescence,Lead halide perovskites,stability,core-shell structure,quantum yield
更新于2025-09-23 15:19:57
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Organic Printed Core-Shell Heterostructure Arrays: A Universal Approach to All-Color Laser Display Panels
摘要： We demonstrate a universal approach for realizing dual-wavelength lasing in organic core-shell structured microlaser arrays, which show great promise in serving as all-color laser display panels. By alternately printing hydrophilic and hydrophobic laser dye solutions on preprocessed substrates, we successfully obtained precisely patterned core-shell heterostructure arrays. The spatially-separated core and shell independently function as optical resonators to support dual-wavelength tunable microlasers in each heterostructure. Such a general method enables to flexibly control the lasing wavelength of the core-shell microlasers across a wide spectral range by systematically designing the gain media. Using as-prepared microlaser arrays as display panels, we achieved full-color laser displays, representing an achievable color gamut much larger than that of standard RGB space. These results may provide new insights for design concepts and device construction for novel optoelectronic applications.
关键词： laser display,organic heterostructure,core-shell structure,dual-wavelength laser,laser array
更新于2025-09-23 15:19:57
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Hierarchical Core-Shell Structure of 2D VS2@VC@N-Doped Carbon Sheets Decorated by Ultrafine Pd Nanoparticles: Assembled in 3D Rosette-like Array on Carbon Fiber Microelectrode for Electrochemical Sensing
摘要： The development of two-dimension (2D) nanohybrid materials with heterogeneous component in nanoscale and three-dimension (3D) well-ordered assembly in microscale has been regarded as an effective way to improve their overall performances by synergistic coupling of the optimized structure and composition. In this work, we reported the design and synthesis of a new type of hierarchically core-shell structure of 2D VS2@VC@N-doped carbon (NC) sheets decorated by ultrafine Pd nanoparticles (PdNPs), which were vertically grown on carbon fiber (CF) and assembled into a unique 3D rosette-like array. The resultant VS2@VC@NC-PdNPs modified CF microelectrode integrated the structural and electrochemical properties of the heterogeneous hybridization of core-shell VS2@VC@NC-PdNPs sheets with unique rosette-like array structure, and gave rise to a significant improvement in terms of electron transfer ability, electrocatalytic activity, stability and biocompatibility. Under the optimized conditions, the VS2@VC@NC-PdNPs modified CF microelectrode demonstrated excellent electrochemical sensing performance towards biomarker hydrogen peroxide (H2O2) including high sensitivity of 152.7 μA cm-2 mM-1, low detection limit of 50 nM (a signal-to-noise ratio of 3:1), as well as good reproducibility and anti-interference ability, which could be used for real-time in situ electrochemical detection of H2O2 in live cancer cells and cancer tissue. The remarkable performances of the proposed nanohybrid microelectrode will have a profound impact on the design of diverse 2D layered materials as promising candidate for electrochemical biosensing applications.
关键词： electrochemical sensing,hierarchical core-shell structure,three-dimension rosette-like sheets array,Two-dimension layered nanomaterials,cancer biomarker detection
更新于2025-09-23 15:19:57