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Tunable and large plasmonic field enhancement in core-shell heterodimer/trimer
摘要： Heterodimer/trimer are two/three closely adjacent nanoparticles dissimilar in shape or size, and represent a simple nanoscale geometry which gives rise to a remarkably rich set of properties. The core-shell nanostructure has advantages of tunability and stability over a similar homogeneous particle. We theoretically demonstrate tunable and significant field enhancement in both heterodimer and heterotrimer systems using core-shell geometry with a metal shell and dielectric core and compared our results with core-shell homodimer and homotrimer. The analytical modeling is based on the Rayleigh theory for small particles and Foldy–Lax multi-scattering theory for multiple particles. It is shown that the E-field can be enhanced in core-shell dimer/trimer due to the plasmonic resonance in the metal shell, which can be easily tunable by changing the core-shell ratio, composition of the core and shell, relative size and distance between the particles, and wavelength of the incident light. We report significant maximum field intensity enhancement near the particles. Moreover, this tunable nanostructures with high field intensity can be useful as potential bio-sensing applications.
关键词： tunability,Foldy–Lax theory,core-shell NPs,Heterotrimer,Rayleigh theory,plasmonic resonance
更新于2025-09-11 14:15:04
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Gold-assembled silica-coated cobalt nanoparticles as efficient magnetic separationunits and surface-enhanced Raman scattering substrate
摘要： Magnetic and optical bifunctional nanoparticles that combine easy separation, preconcentration, and efficient SERS capabilities have been fabricated with high sensitivity and reproducibility through a low-cost method. These gold nanoparticles attached on magnetic silica-coated cobalt nanospheres (Co@SiO 2 /AuNPs) display the advantage of strong resonance absorption due to gaps at nanoscale between neighboring metal nanoparticles bringing large field enhancements, known as “hot spots”. The prepared particles can be controlled by using an external magnetic field, which makes them very promising candidates in biological applications and Raman spectroscopic analysis of dissolved organic species. The magnetic property of the prepared particles lowers the detection limits through preconcentration with solid-phase extraction in SERS analysis. The performance of the prepared nanostructures was evaluated as a SERS substrate using brilliant cresyl blue (BCB) and rhodamine 6G (R6G) as model compounds. The solid-phase affinity extraction of 4-mercapto benzoic acid (4-MBA) using bifunctional Co@SiO 2 /AuNPs nanoparticles followed by magnetic separation and the measurement of the SERS signal on the same magnetic particles without elution were investigated. Approximately 50-fold increase in SERS intensity was achieved through solid-phase extraction of 8.3 × 10 (cid:0)6 M 4-MBA in 10 min.
关键词： surface modification,Bifunctional nanoparticles,preconcentration,surface enhanced Raman scattering,core-shell nanoparticles,magnetic separation
更新于2025-09-11 14:15:04
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Enhancing the Photovoltaic Performance of Perovskite Solar Cells Using Plasmonic Au@Pt@Au Core-Shell Nanoparticles
摘要： Au@Pt@Au core-shell nanoparticles, synthesized through chemical reduction, are utilized to improve the photoelectric performance of perovskite solar cells (PSCs) in which carbon films are used as the counter electrode, and the hole-transporting layer is not used. After a series of experiments, these Au@Pt@Au core-shell nanoparticles are optimized and demonstrate outstanding optical and electrical properties due to their local surface plasmon resonance and scattering effects. PSC devices containing 1 wt.% Au@Pt@Au core-shell nanoparticles have the highest efficiency; this is attributable to their significant light trapping and utilization capabilities, which are the result of the distinctive structure of the nanoparticles. The power conversion efficiency of PSCs, with an optimal content of plasmonic nanoparticles (1 wt.%), increased 8.1%, compared to normal PSCs, which was from 12.4% to 13.4%; their short-circuit current density also increased by 5.4%, from 20.5 mA·cm?2 to 21.6 mA·cm?2. The open-circuit voltages remaining are essentially unchanged. When the number of Au@Pt@Au core-shell nanoparticles in the mesoporous TiO2 layer increases, the photovoltaic parameters of the former shows a downward trend due to the recombination of electrons and holes, as well as the decrease in electron transporting pathways.
关键词： perovskite solar cells,Au@Pt@Au core-shell nanoparticles,mesoporous TiO2
更新于2025-09-11 14:15:04
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Theoretical calculation of optical absorption property of Cu@Ag core–shell composite nanoparticle
摘要： Because of their unique surface plasmon resonance (SPR) absorption in the visible region of the electromagnetic (EM) wavelength, plasmonic nanoparticles (NPs) such as gold (Au), silver (Ag) and copper (Cu) are utilized to combine with another material in devices. In this work, the optical absorption property exhibited by core–shell NPs composed of Cu cores with Ag shells (Cu@Ag) was investigated by the Discrete Dipole Approximation (DDA) method. In the theoretical calculation, at ?rst, the Ag shell thickness was ?xed at 5 nm and the Cu core diameters were varied between 10 and 30 nm. Second, the Cu core size was ?xed at 20 nm and the Ag shell thickness was varied from 2 nm to 10 nm. It was observed that as the size of the Cu core increased with a ?xed Ag shell thickness, the absorption peak gradually shifted to that of the pure Cu peaks (at ～358 nm and ～510 nm). On the other hand, the increasing Ag shell thickness showed the shifting of the absorption peak to the absorption peak of pure Ag NP (～432 nm). The results revealed that varying either the Cu core size or the Ag shell thickness could result in obtaining tuneable light absorption. Such typical nanomaterials are expected to ?nd application in future medical, solar cell and novel functional devices.
关键词： discrete dipole approximation,Cu@Ag core-shell,localized surface plasmon resonance
更新于2025-09-11 14:15:04
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Double protected lanthanide fluorescence core@shell colloidal hybrid for the selective and sensitive detection of ClO-
摘要： Without any surfactant or organic solvent, a water-borne method incorporated a biphasic sol-gel process and a Pickering emulsion process was firstly applied to encapsulate lanthanide complexes. Compared with the free one, the achieved double protected lanthanide fluorescence colloidal hybrid particles with core@shells structure has a specific ClO- detection with high selectivity and sensitivity in contrast with other inorganic ions including Cu2+, Fe3+ and other strong acids. With strong oxidation characteristics, ClO- can gradually penetrate through silica shell, and quench the red fluorescence of lanthanide ions in the organosilica core. This core@shell colloidal nanoprobe exhibits an excellent sensing capacity for hypochlorite in real sample. This green environment friendly method could be easily extended to form functional hybrid particles with other types of reactive oils and nanoparticles for devising other specified fluorescent sensors.
关键词： Core@shell,Hypochlorite,Organosilica,Fluorescence,Pickering emulsion
更新于2025-09-11 14:15:04
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Polydopamine-inspired Design and Synthesis of Visible-light-driven Ag NPs@C@elongated TiO2 NTs Core-shell Nanocomposites for Sustainable Hydrogen Generation
摘要： The primary challenge of photocatalytic hydrogen generation is to exploit a catalyst with good durability and low cost. Here, we designed a facile and efficient process of loading silver nanoparticles (Ag NPs) in situ on the core-shell nanocomposite of the elongated titanium dioxide nanotubes with carbon layer (C@TiO2 NTs) by polydopamine (PDA) without addition of any binder. The combination of C@TiO2 NTs with Ag NPs has excellent performance toward photocatalytic hydrogen production and degradation of rhodamine B (RhB) under visible light irradiation. The characterizations (SEM, TAM, XRD, XPS, etc.) showed that the carbon layer on nanotubes could conformably cover the whole of TiO2 NTs to form core-shell structure, which not only prevented Ag NPs from aggregating, but also acted as the electronic transport channel. Meanwhile, Ag NPs were uniformly distributed on the surface of C@TiO2 NTs. In conclusion, under the synergistic effect of Ag nanoparticles and outer-carbon layer, the utilization efficiency of visible light has been enhanced and the recombination of electrons/holes has been suppressed for Ag@C@TiO2 NTs nanocomposites. Therefore, the degradation efficiency of RhB and hydrogen generation rate is 2.5 times and 4.8 times as higher as pure TiO2 NTs, respectively. This work may provide fruitful experience for developing novel strategy into the design and fabrication of stable and highly active visible-light catalysts with noble metal modification toward sustainable hydrogen production in the energy filed.
关键词： elongated TiO2 nanotube,carbon shell,Ag nanoparticle,visible-light induced photo-catalyst,core-shell structure
更新于2025-09-10 09:29:36
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Eccentric metallo-dielectric core-shell nanoparticles for switching and guiding purposes
摘要： Metallo-dielectric or dielectric-dielectric core-shell nanoparticles have been proposed during last years for enhancing the near Zero-Forward and Zero-Backward conditions because they support tunable electric and magnetic resonances. By changing the relative size of the core respect to the particle size, electric and magnetic resonances are shifted. As a consequence, they can be used to control the direction of the scattered radiation. Here, we demonstrate the possibility of using isolated eccentric metallo-dielectric core-shell nanoparticles for redirecting the incident radiation into some specific directions eventually different from the forward and backward ones. In particular, we show their utility for building operational switching devices, whose on/off state only depends on the polarization of the incident radiation. Chains of these scattering units have shown good radiation guiding effects at the nanoscale level.
关键词： metallo-dielectric,core-shell nanoparticles,scattering directionality,radiation guiding,switching devices
更新于2025-09-10 09:29:36
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From nano-structured polycrystalline spheres with Zn1-xCoxO composition to core-shell Zn1-xCoxO@SiO2 as green pigments
摘要： ZnO doped with Co2+, a well-known green pigment which is an alternative to the chromium based inorganic pigments, has been prepared by a polyol process and investigated in terms of crystallographic structure and UV?visible properties. Thanks to the obtaining of nanometric crystallite size from our process, the incorporation of a very high concentration of Co2+ in the ZnO matrix is achieved. Thus, different grades of more or less deep green pigments can be produced. Furthermore, the obtaining of spherical aggregates allows the easy preparation of ZnO:Co@SiO2 core-shells, minimizing hence the problems linked to the zinc oxide high solubility into slightly acidic conditions acidic conditions and the metal cation’s toxicity.
关键词： Core-shell,Zinc-Cobalt oxide,Green Pigment,Polyol synthesis
更新于2025-09-10 09:29:36
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Investigation of thermal stability of 2D and 3D CoAl2O4 particles in core-shell nanostructures by Raman spectroscopy
摘要： We are studying the formation of a nanostructured spinel CoAl2O4 layer on α-Al2O3 giving rise to a core-shell composite. In the final product, two mechanisms of CoAl2O4 crystallization onto a α-Al2O3 microparticle surface are observed, depending on the dispersion grade of Co3O4: a 3D nanostructure from the arrangement of Co3O4 agglomerated nanoparticles; 2D nanoparticles from the diffusion mechanism of isolated Co3O4 nanoparticles. As a consequence, two different crystallization pathways may occur during the thermal treatment. In order to understand the formation mechanisms a Raman Confocal Study is performed. The features of the Raman spectra of the samples depend strongly on the morphology of the nanoparticles located in the shell of the microparticle. Average spectra of the samples show a variation in the Raman shift between the different samples. The differences between 3D or 2D structures is associated with the transmission of phonons among the nanoparticles. The high absorbance of the cobalt species could mask the Raman shift displacement by local heating, so both the temperature and the laser source power are considered in the Raman study. The evolution of the Raman spectra with applied temperature indicates a decoupling of the Raman modes. This fact is more relevant for the 3D aggregates in which nanoparticles produced a larger scattering of phonons and a higher sensitivity to temperature variation. These results clearly indicate that extrinsic parameters such as the size of the crystals and their aggregation state affects their Raman properties.
关键词： Confocal Raman microscopy,Dry dispersion,Core-shell,CoAl2O4 spinel
更新于2025-09-10 09:29:36
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Tuning and enhancing the red upconversion emission of Er3+ in LiYF4 nanoparticles
摘要： The tetragonal-phased LiYF4:Yb3+/Er3+ nanoparticles with different core-shell nanostructures have been successfully synthesized by a modified solution-based method. The upconversion emissions of LiYF4: Yb3+/Er3+ nanoparticles were precisely tuned from green to red with the increase in Yb3+ concentrations under 980 nm excitation. The corresponding intensity ratios of the red and green emissions (R/G ratios) were enhanced from 0.06 to 5.33. However, the overall integral upconversion intensity of LiYF4:Yb3+/Er3+ nanoparticles clearly decreased when the Yb3+ doping concentrations were increased. For the enhancement of the red upconversion intensity and expansion of their application, two kinds of core-shell nanostructures, namely, LiYbF4:Er3+@LiYF4 and LiYbF4:Er3+@LiYbF4, were constructed through epitaxial growth at similar experimental conditions. The LiYbF4:Er3+@LiYF4 core-shell nanostructures exhibited stronger upconversion emission and higher R/G ratios than the LiYbF4:Er3+ and LiYbF4:Er3+@LiYbF4 nanoparticles. The highest R/G ratios increased to 6.27 in LiYbF4:Er3+@LiYF4 core-shell nanostructures, increasing 104-fold. The upconversion regulation and enhancing mechanism were also discussed according to the emission spectra and fluorescence lifetimes.
关键词： upconversion,LiYF4 nanoparticles,core/shell nanostructures,cross relaxation
更新于2025-09-10 09:29:36