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Bi <sub/>2</sub> SiO <sub/>5</sub> @g-SiO <sub/>2</sub> upconverting nanoparticles: a bismuth-driven core–shell self-assembly mechanism
摘要： Core–shell systems have attracted increasing interest among the research community in recent years due to their unique properties and structural features, and the development of new synthetic strategies is still a challenge. In this work, we have investigated lanthanide-doped Bi2SiO5 nanocrystal formation inside mesoporous silica nanoparticles (MSNs). The role of both synthesis temperature and concentration of the bismuth precursor impregnated into the MSNs is discussed, showing an unprecedented strategy for the simultaneous stabilization of a crystalline core and a glassy shell. Temperature dependent synchrotron radiation X-ray powder diffraction (SR-XRPD) and high resolution transmission electron microscopy (HR-TEM) analyses allow one to follow the crystalline core growth. A mechanism for the formation of a Bi2SiO5@g-SiO2 core–shell nanosystem is proposed. In addition, the easy tunability of the color output of the upconverting system is demonstrated by means of suitable doping lanthanide ions with potential applications in several fields.
关键词： upconversion luminescence,mesoporous silica,core–shell nanoparticles,bismuth silicate,Bi2SiO5
更新于2025-09-19 17:15:36
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Enhanced gas-sensing performance of metal@ZnO core–shell nanoparticles towards ppb–ppm level benzene: the role of metal–ZnO hetero-interfaces
摘要： Core–shell metal@ZnO nanoparticles including Au@ZnO, Pd@ZnO and Pt@ZnO were synthesized and utilized for sensing low-concentration benzene. Various techniques were used to characterize the compositional properties of the typical core@shell structure and analyze the relation between the sensing properties and the metal–ZnO hetero-interfaces. When applied as gas-sensing materials, all three core–shell metal@ZnO nanoparticles showed better sensing performance than pure ZnO nanoparticles towards low concentration benzene. In particular, the gas-sensing response of the Pt@ZnO core–shell nanoparticles was 7 times higher than that of pure ZnO towards 0.1 ppm benzene and 63 times higher towards 5 ppm benzene, which was more sensitive than most gas-sensing materials in previous literature. Furthermore, the Pt@ZnO core–shell nanoparticles presented an ultra-low detection limit of no less than 10 ppb, which was lower than those of most gas-sensing materials in previous literature. Besides, the Pt@ZnO core–shell nanoparticles showed high selectivity and long-term response stability with a response value of 2.7 ± 1.6% towards 1 ppm benzene after operating for a month. The enhanced gas-sensing performances of the metal@ZnO core–shell nanoparticles are well correlated to the work function differences between the contacted metal and ZnO within the metal–ZnO hetero-interfaces, which produce high Schottky energy barriers and modulate the electron transfer.
关键词： gas-sensing,Schottky barrier,core–shell nanoparticles,benzene,metal–ZnO hetero-interfaces
更新于2025-09-19 17:15:36
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Grain Boundary and Interface Passivation with Corea??Shell Au@CdS Nanospheres for Higha??Efficiency Perovskite Solar Cells
摘要： The plasmonic characteristic of core–shell nanomaterials can effectively improve exciton-generation/dissociation and carrier-transfer/collection. In this work, a new strategy based on core–shell Au@CdS nanospheres is introduced to passivate perovskite grain boundaries (GBs) and the perovskite/hole transport layer interface via an antisolvent process. These core–shell Au@CdS nanoparticles can trigger heterogeneous nucleation of the perovskite precursor for high-quality perovskite films through the formation of the intermediate Au@CdS–PbI2 adduct, which can lower the valence band maximum of the 2,2,7,7-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9-spirobifluorene (Spiro-OMeTAD) for a more favorable energy alignment with the perovskite material. With the help of the localized surface plasmon resonance effect of Au@CdS, holes can easily overcome the barrier at the perovskite/Spiro-OMeTAD interface (or GBs) through the bridge of the intermediate Au@CdS–PbI2, avoiding the carrier accumulation, and suppress the carrier trap recombination at the Spiro-OMeTAD/perovskite interface. Consequently, the Au@CdS-based perovskite solar cell device achieves a high efficiency of over 21%, with excellent stability of ≈90% retention of initial power conversion efficiencies after 45 days storage in dry air.
关键词： perovskite photovoltaic devices,interface passivation,Au@CdS,core–shell nanoparticles
更新于2025-09-19 17:13:59
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Plasmonic mesoporous core-shell Ag-Au@TiO2 photoanodes for efficient light harvesting in dye sensitized solar cells
摘要： In this study, plasmonic mesoporous core-shell Ag-Au@TiO2 nanocomposites were synthesized by seed-mediated growth of Ag shell onto Au decorated TiO2 and utilized as photoanodes to enhance the power conversion efficiency (PCE) of dye-sensitized solar cells. The enhanced preserved mesoporous characteristics of photoanodes, together with strong metal-dielectric interfacial interaction between Ag-Au shell, remarkably improved electron transfer ability onto TiO2, which caused to the enhancement of the light harvesting (η = 7.41% using Ag-Au@TiO2) 125% higher than bare TiO2 (η = 5.91%). These superior PCE value was mainly due to the shifting of the Fermi level close to the TiO2 conduction band thanks to the broad band localized surface plasmon resonance (LSPR) properties between Ag-Au and TiO2 interfaces. The significant outperforming in enhanced solar to electrical energy conversion efficiency using low amount of Ag-Au@TiO2 photoanode (0.0125 wt%) demonstrated a relative low-cost solar device from the economic perspective of renewable energy fabrication resources.
关键词： Metal core-shell nanoparticles,Mesoporous structures,Plasmonic TiO2,Dye-sensitized solar cells,Localized surface plasmon resonance
更新于2025-09-19 17:13:59
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Effect of molarities on structural and optical properties of type-II heterostructure CdS/PbS core/shell quantum dot
摘要： The interrelation between particle sizes and crystal structure in core/shell (CS) semiconductor quantum dots has elicited widespread interest. The effects of precursor concentration of chemically synthesized CdS/PbS CS nanoparticles on structural and optical properties have been reported. CdS/PbS CS QDs shows polycrystalline nature with hexagonal phase in X-ray Diffraction (XRD) pattern, which was also confirmed from SEAD pattern. The particle size was found about 15 nm from the HRTEM images, which was also exhibited CS structure of the NPs. EDX and XRD pattern exhibited the formation of pure CdS/PbS CS structure NPs. The strain in the small spherical NPs is dominant; resulting is shifting of XRD peaks towards higher 2θ values and is found to decrease with an increased crystal size of the core. The effect of molarities on the size of the NPs has seen in the absorption spectra and emission spectra with red shifted. The bandgap of the CS NPs varies inversely with the molar concentration of the nanocrystals. The luminescence intensity exhibited increasing trend with the molar concentration of the nanocrystals. The optical properties were found to be in agreement with the structural properties of the CS NPs.
关键词： Molarities effect,Structural properties,Optical properties,CdS/PbS,Core/shell nanoparticles
更新于2025-09-16 10:30:52
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Multiplexed surface plasmon imaging of serum biomolecules: Fe3O4@Au Core/shell nanoparticles with plasmonic simulation insights
摘要： Nano-biosensors that are not only sensitive and selective, but also enable multiplex detection of ultra-low levels of both large and small biomolecules in clinical sample matrices are essential for in vitro diagnostics. We present herein a multiplex surface plasmon microarray design that employs citrate-stabilized Fe3O4@Au core/shell nanoparticles (NPs) as the plasmon signal ampli?cation label for combined detection of serum proteins and nucleotide markers. The multiplex sensing is demonstrated using two interleukins (IL-6 and IL-8) and two microRNAs (miRNA-21 and miRNA-155) in 10% serum, which is clinically relevant than simple bu?er solution based biosensors. We observed that the surface plasmon signal change for larger proteins even at higher concentrations was less than the relatively smaller miRNA molecules. We draw two conclusions from this result: (i) the number of selectively bound analytes onto the sensor (i.e., antigen for an antibody or miRNA for a capture nucleotide) in?uences the signal change, and (ii) the extent of interaction of the detection probe carrying core/shell NP labels with the sensor surface plasmons in?uences the amount of signal change. Results indicate that both factors, (i) and (ii), are greater for small oligonucleotide hybridization assembly than a large sandwich protein immunoassembly. The core/shell NPs o?ered several fold enhanced sensitivity and wider dynamic range of detection over assays without using them. With recently growing attention on in vitro diagnostics for painless/minimally-invasive detection of diseases and abnormalities, ?ndings presented herein are important for designing novel multiplex biosensors for real sample analysis in complex matrices.
关键词： serum proteins,wide dynamic range,serum miRNAs,Multiplex imaging,core/shell nanoparticles,FDTD simulation
更新于2025-09-16 10:30:52
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Application of Core–Shell Metallic Nanoparticles in Hybridized Perovskite Solar Cell—Various Channels of Plasmon Photovoltaic Effect
摘要： We analyze the microscopic mechanism of the improvement of solar cell efficiency by plasmons in metallic components embedded in active optical medium of a cell. We focus on the explanation of the observed new channel of plasmon photovoltaic effect related to the influence of plasmons onto the internal cell electricity beyond the previously known plasmon mediated absorption of photons. The model situation we analyze is the hybrid chemical perovskite solar cell CH3NH3PbI3?αClα with inclusion of core–shell Au/Si02 nanoparticles filling pores in the Al2O3 or TiO2 porous bases at the bottom of perovskite layer, application of which improved the cell efficiency from 10.7 to 11.4% and from 8.4 to 9.5%, respectively, as demonstrated experimentally, mostly due to the reduction by plasmons of the exciton binding energy.
关键词： plasmons,perovskite solar cells,plasmon photo-effect,core–shell nanoparticles,metallized cells
更新于2025-09-16 10:30:52
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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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[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