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Theoretical Calculation of the Optical Properties of Dielectric Material @ Noble Metal Core-Shell Composite Nanoparticles
摘要： Objectives: Methods: Surface plasmon exhibited in nano-sized particles such as gold, silver, copper has recently attracted a great deal of attention due to the enhancement and tunable optical properties in the visible to near-infrared region of the electromagnetic spectrum. In this work, the optical properties of dielectric material at noble metal core-shell nanoparticles Mie theory is the analytical method is used to study via parameters of extinction, scattering and absorption efficiencies. The samples for studying were the composites of a dielectric material core coated by a thin noble metal (Ag, Au, and Cu). The core size was fixed at 50 nm, while the metal shell thicknesses were varied from 3 nm to 40 nm. The calculated optical properties were found that the surface plasmon resonance can be enhanced and tuned the wavelength from the near ultraviolet to near infrared regions by varying the shell thickness. The dielectric core coated with a thin noble metal to promote the properties of the core can be applied in the field of plasmonic nanolaser, nonlinear plasmonic antenna, light trapping in thin-film organic solar cells, and biomedical research.
关键词： Dielectric Material @ Noble Metal Core-Shell,Surface Plasmon
更新于2025-09-10 09:29:36
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SERS-based lateral flow immunoassay of troponin I by using gap-enhanced Raman tags
摘要： The lateral flow immunoassay (LFIA) has emerged as a powerful tool for rapid screening owing to its simplicity and flexibility for detection of various biomarkers. However, conventional LFIA strips have several disadvantages, including limits in quantitative analysis and low sensitivity. Here we developed a novel surface-enhanced Raman scattering LFIA based on nonspherical gap-enhanced Raman tags (GERTs), with Raman molecules (RMs) embedded in a 1-nm gap between Au nanorod core and Au shell. Such tags have a strong and uniform SERS response, an order of magnitude higher than that of other common SERS tags such as Au nanorods, nanostars, Au nanoshells with surface-adsorbed RMs, or spherical GERTs with embedded RMs. The feasibility of the tags was demonstrated by the semiquantitative and sensitive detection of the heart disease biomarker cardiac troponin I (cTnI). GERTs were conjugated with monoclonal antibodies and used for LFIA in the same way as ordinary functionalized colloidal gold. The presence of the target antigen, cTnI, was identified by Raman microscopy mapping of the test zone. With the SERS-based LFIA, the limit of cTnI detection was about 0.1 ng/mL. This value is within the diagnostic range of cTnI in the blood serum of patients with heart infarction and is 30 times lower than that of the colorimetric LFIA test using the same antibodies and either GERTs or colloidal gold as labels.
关键词： gap-enhanced Raman tags,lateral flow immunoassay,SERS,cardiac Troponin I,Au core/shell nanorods
更新于2025-09-10 09:29:36
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Preparation of core–shell nanostructured black nano-TiO <sub/>2</sub> by sol–gel method combined with Mg reduction
摘要： Black nano-TiO2 samples with core–shell nanostructure were successfully prepared by sol–gel method combined with Mg reduction using butyl titanate as titanium source and calcining at 500°C in air atmosphere and at 400–600°C in nitrogen atmosphere. The prepared black TiO2 samples were characterized by X-ray diffraction, high resolution transmission electron microscopy, Raman spectra, photoluminescence emission spectra, N2 adsorption–desorption, and ultraviolet–visible spectroscopy. The results show that the black TiO2 exhibits a crystalline core–disordered shell structure composed of disordered surface and oxygen vacancies, and the thickness of the disordered layer is about 2–3 nm. The optical absorption properties of black nano-TiO2 samples have been remarkably enhanced in visible light region. Compared with the white TiO2, the reduced black TiO2 samples exhibit enhanced photocatalytic hydrogen production under the full solar wavelength range of light, and the sample prepared with the Mg and TiO2 ratio of 9:1 calcined at 500 °C has the maximum hydrogen production rate.
关键词： core–shell nanostructure,Black nano-TiO2,photocatalytic hydrogen production,sol–gel method,Mg reduction
更新于2025-09-10 09:29:36
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Metal-Enhanced Fluorescence of Gold Nanoclusters as a Sensing Platform for Multi-component Detection
摘要： Metal-enhanced fluorescence (MEF) has been applied to construct biosensing systems in the recent decades owing to its favorable optical properties. Herein, silver nanoparticles (AgNPs) are used to enhance fluorescence of gold nanoclusters (AuNCs), by fabricating a core-shell composite nanostructure Ag@SiO2-AuNCs consisting of a silver core, a silica shell and an outer conjugated layer of AuNCs. The core-shell MEF-capable nanoparticles possess water dispersibility, high stability and good biocompatibility. The interaction between AuNCs on the surface of the outer silica shell and the silver core, significantly improves the excitation efficiency, and thus enhances the fluorescence emission, photostability and quantum yield of the AuNCs. The composite nanoparticle Ag@SiO2-AuNCs provides a fluorescence enhancement of up to 3.21-fold when the separation distance (the thickness of the silica shell) is about 10 nm. Finally, the composite nanostructures have further been applied to develop a sensing platform for multi-component detection based on the MEF capability and the OFF-ON-OFF switching nature of the fluorescence signal, and the detection limits for Cu2+, inorganic pyrophosphate (PPi) and pyrophosphatase (PPase) are 39 nM, 78.7 nM and 0.976 mU, respectively. This platform has been applied to detect Cu2+, PPi and PPase with satisfactory results in living cells.
关键词： Metal-enhanced fluorescence (MEF),Fluorescence sensor,Core-shell composite nanostructure,Gold nanoclusters (AuNCs)
更新于2025-09-10 09:29:36
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Enhanced dielectric, electromechanical and hydrophobic behaviors of core-shell AgNWs@SiO2/PDMS composites
摘要： This paper reports a feasible method to prepare polymeric nanocomposites with enhanced dielectric, electromechanical and hydrophobic performance by introducing the core-shell AgNWs@SiO2 filler into polydimethylsiloxane (PDMS). The homogenous core-shell AgNWs@SiO2 was firstly synthesized through a two-step sol-gel process. The thicknesses of AgNWs and SiO2 coating layer are approximately 70 nm and 20 nm, respectively. The dielectric constant is improved effectively due to enhanced interfacial polarization, while extremely low dielectric loss and conductivity are achieved by introducing the insulating SiO2 interlayer to moderate the internal surface area of core-shell nanowires and restrict the electron transfer between Ag nanowires. Typically, the PDMS nanocomposites with 20 wt% AgNWs@SiO2 have a dielectric constant of 6.7, nearly 2.7 times larger than that of pure PDMS, and remains a quite low loss of 0.02 at 1 kHz. Meanwhile, nanocomposites also show improved electromechanical and hydrophoic properties. Nanocomposites with 10 wt% AgNWs@SiO2 exhibit the highest electromechanical sensitivity (β=9.04), about 12.6 times higher than that of pure PDMS at 1 kHz. The static contact angle of nanocomposties with 20 wt% AgNWs@SiO2 reaches 129°. All the improved performances show great potential application for dielectric elastomer material and electrowetting devices.
关键词： Dielectric properties,Electromechanical properties,Core-shell structure,Interfacial polarization
更新于2025-09-10 09:29:36
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CS@MnO2 core-shell nanospheres with enhanced visible light photocatalytic degradation
摘要： Flower-like core-shell MnO2-coated carbon aerogels (CS@MnO2) were prepared via a facile hydrothermal process. CS@MnO2 composites can remove aqueous solution of dyes, such as Methylene blue (MB), Congo red (CR), and Rhodamine B (RhB). CS@MnO2 presents an excellent decolorization effect of anionic and cationic dyes. Notably, the maximum decolorization rate for cationic dyes reached 99.5% (wt%), together with a decolorization rate of 90% for the anionic dye. Our work not only developed CS@MnO2 core-shell nanospheres as a superior photocatalyst, but also provided a new strategy for many other related applications.
关键词： photocatalysis,Carbon materials,Nanocomposites,core-shell spheres
更新于2025-09-10 09:29:36
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Direct imaging of Indium-rich triangular nanoprisms self-organized formed at the edges of InGaN/GaN core-shell nanorods
摘要： Higher indium incorporation in self-organized triangular nanoprisms at the edges of InGaN/GaN core-shell nanorods is directly evidenced by spectral cathodoluminescence microscopy in a scanning transmission electron microscope. The nanoprisms are terminated by three 46 nm wide a-plane nanofacets with sharp interfaces forming a well-defined equilateral triangular base in the basal plane. Redshifted InGaN luminescence and brighter Z-contrast are resolved for these structures compared to the InGaN layers on the nanorod sidewalls, which is attributed to at least 4 % higher indium content. Detailed analysis of the inner optical and structural properties reveals luminescence contributions from 417 nm up to 500 nm peak wavelength proving the increasing indium concentration inside the nanoprism towards the nanorod surface.
关键词： cathodoluminescence microscopy,InGaN/GaN core-shell nanorods,nanoprisms,scanning transmission electron microscope,indium incorporation
更新于2025-09-10 09:29:36
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Direct Growth of a Polypyrrole Aerogel on Hollow CuS Hierarchical Microspheres Yields Particles with Excellent Electromagnetic Wave Properties
摘要： A current hot topic in polymer science is the development of electromagnetic wave-absorbing materials with desired properties (i.e., proper impedance matching and strong attenuation capability), but it presents a considerable challenge. In this work, solvothermal, and self-assembled polymerization were employed for the controlled fabrication of a uniform polypyrrole (PPy) aerogel coated on hollow CuS hierarchical microspheres (CuS@PPy). The PPy coating thickness of the heterostructure could be tuned by varying the feeding weight ratios of CuS/pyrrole monomer. The electromagnetic wave absorption properties of the CuS@PPy composites were estimated to be in the frequency range 2–18 GHz. The as-prepared Sample B (fabricated by the addition of 35 mg CuS) showed a maximum re?ection loss (RL) of ?52.85 dB at a thickness of 2.5 mm. Moreover, an ultra-wide effective bandwidth (RL ≤ ?10 dB) from 9.78 to 17.80 GHz (8.02 GHz) was achieved. Analysis of the electromagnetic properties demonstrated that the CuS@PPy had a remarkable enhancement compared to pure CuS platelet-based spheres and pure PPy, which can be attributed to the increased relatively complex permittivity and the promoted dielectric loss by the intense interfacial dielectric polarizations. We believe that the as-fabricated CuS@PPy can be a good reference for the fabrication of lightweight and optimal broadband absorbers.
关键词： core–shell,dielectric loss,electromagnetic absorption,polypyrrole
更新于2025-09-10 09:29:36
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Evolution of the Ligand Shell around Small ZnO Nanoparticles during the Exchange of Acetate by Catechol: A Small Angle Scattering Study
摘要： The core-shell structure of colloids surrounded by ligands is of great importance for their later application as it can significantly alter the chemical and physical properties of the nanoparticles (NPs). A combination of small angle X-ray and neutron scattering (SAXS/SANS) the native solution with additional ex situ measurements (titration-UV) was applied to study the NP/ligand interface of ZnO NPs after functionalization with catechol derivatives. Based on SAXS data, it was found that within the multimodal particle size distribution the fraction of agglomerates is shifted to smaller sizes and nearly disappeared upon the binding of ethyl 3,4-dihydroxybenzoate (CAT) molecules. This is ascribed to improved stabilization at the primary particle level by CAT molecules. By combining the neutron scattering contrast with the input of bound CAT molecules from a previously developed titration-UV method, the heterogeneous composition of the ligand shell became accessible for the first time.
关键词： small angle scattering,quantum dots,in situ analysis,ligand exchange,core-shell
更新于2025-09-10 09:29:36
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Design and Comparative Studies of Z-Scheme and Type II Based Heterostructures of NaNbO <sub/>3</sub> /CuInS <sub/>2</sub> /In <sub/>2</sub> S <sub/>3</sub> for Efficient Photoelectrochemical Applications
摘要： Here, we report the fabrication of a new Z-scheme based core/shell/shell heterostructure of NaNbO3/CuInS2/In2S3 (core/shell/shell) for photoelectrochemical (PEC) water splitting and also for degradation of organic pollutants. We have also performed a comparative study with a modified heterostructure of NaNbO3/In2S3/CuInS2 having Type II band alignment. The PEC measurements under visible light irradiation show increased photocatalytic performance for the NaNbO3/CuInS2/In2S3 heterostructures as revealed by a high current density of ～6.72 mA/cm2 at ?1.0 V versus Ag/AgCl and low photocurrent onset potential of ～?110 mV in comparison to the Type II system (～1.63 mA/cm2 and ?180 mV vs Ag/AgCl). Mott?Schottky plots confirmed the n?p?n type heterojunction formation in the NaNbO3/CuInS2/In2S3 heterostructure which reduces the charge carrier recombination (revealed by PL intensity and short lifetime). The Z-scheme based system also exhibits excellent degradation efficiency (～99.6%) of organic pollutants. This work shows that the Z-scheme charge separation mechanism in NaNbO3/CuInS2/In2S3 nanostructures is more efficient than the Type II based on NaNbO3/In2S3/CuInS2.
关键词： core/shell/shell heterostructure,photoelectrochemical water splitting,Type II band alignment,organic pollutants degradation,Z-scheme,NaNbO3/CuInS2/In2S3
更新于2025-09-09 09:28:46