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High-performance electrochromic device based on novel polyaniline nanofibers wrapped antimony-doped tin oxide/TiO2 nanorods
摘要： We report a novel electrochromic device (ECD) using polyaniline nanofibers wrapped antimony-doped tin oxide/TiO2 (ATO/TiO2@PANI) nanorods as electrochromic electrode material. The nanocomposites with core-shell structure were prepared by in situ chemical oxidative polymerization where aniline was polymerized in ATO/TiO2 nanorods aqueous dispersion. PEDOT:PSS film which was a complementary coloring material was used as counter electrode. A gel electrolyte (GE) was used in ECD. The architectural design of ECD based on ATO/TiO2@PANI film was ITO/ATO-TiO2@PANI/GE/PEDOT:PSS/ITO (ECD-TPN). Compared with the ECD based on pure PANI film (ECD-PANI), higher optical contrast (38.5% at 660nm), higher coloration efficiency 202.2 cm2/C, faster response speed (tc=1.2 s, tb=1.0 s) and better cycling stability (sustaining 99.5% of its initial optical modulation after subjecting 5000 s) are archived by the ECD-TPN. The enhanced electrochromic properties are mainly attributed to the formation of the donor-acceptor system between the PANI nanofiber shell layer and the ATO/TiO2 nanorod, and the porous space among the ATO/TiO2@PANI nanocompsites and the PANI nanofibers, which can improve the efficiency of redox reaction, make the ion diffusion easier and provide larger surface area for charge-transfer reactions, respectively.
关键词： Chemical oxidative polymerization,ATO/TiO2,Electrochromism,Core-shell nanostructures,Polyaniline
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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Excitonic Aharonov-Bohm Oscillations in Core-Shell Nanowires
摘要： Phase coherence in nanostructures is at the heart of a wide range of quantum effects such as Josephson oscillations between exciton–polariton condensates in microcavities, conductance quantization in 1D ballistic transport, or the optical (excitonic) Aharonov–Bohm effect in semiconductor quantum rings. These effects only occur in structures of the highest perfection. The 2D semiconductor heterostructures required for the observation of Aharonov–Bohm oscillations have proved to be particularly demanding, since interface roughness or alloy fluctuations cause a loss of the spatial phase coherence of excitons, and ultimately induce exciton localization. Experimental work in this field has so far relied on either self-assembled ring structures with very limited control of shape and dimension or on lithographically defined nanorings that suffer from the detrimental effects of free surfaces. Here, it is demonstrated that nanowires are an ideal platform for studies of the Aharonov–Bohm effect of neutral and charged excitons, as they facilitate the controlled fabrication of nearly ideal quantum rings by combining all-binary radial heterostructures with axial crystal-phase quantum structures. Thanks to the atomically flat interfaces and the absence of alloy disorder, excitonic phase coherence is preserved even in rings with circumferences as large as 200 nm.
关键词： excitonic Aharonov–Bohm effect,phase coherence,core–shell nanowires,3D nanostructures
更新于2025-09-23 15:21:01
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Different Silver Nanoparticles in One Crystal: Ag210(iPrPhS)71(Ph3P)5Cl and Ag211(iPrPhS)71(Ph3P)6Cl
摘要： Two pure silver nanoparticles (Ag210(iPrPhS)71(Ph3P)5Cl and Ag211(iPrPhS)71(Ph3P)6Cl labeled as SD/Ag210 and SD/Ag211 (SD = SunDi), were found to co-crystallize in forming compound 1. Single-crystal X-ray diffraction (SCXRD) revealed that they differ by only one Ag(PPh3). Their four-shell nanoparticles consist of three pure Ag metal shells (Ag19@Ag52@Ag45) shielded by a silver-organic Ag89(iPrPhS)71Cl[Ag(Ph3P)]n. outermost shell. The number (n) of Ag(Ph3P) is five for SD/Ag210 and six for SD/Ag211. The pseudo-fivefold symmetric Ag nanoparticles exhibit surface plasmon absorption similar to a true metallic state but at the nanoscale. The attributes of this work are i) it exemplifies the important effects of phosphine in stabilizing large silver nanoparticles; ii) it offers a platform to investigate the origin of differences in nanoscale metal materials, even differing by only one metal atom; and iii) it sheds light on the regioselective binding of auxiliary Ph3P on the surface of silver nanoparticles.
关键词： co-crystallization,core-shell,silver nanoparticles,alkyne,surface plasmon
更新于2025-09-23 15:21:01
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From core-shell to yolk-shell: Keeping the intimately contacted interface for plasmonic metal@semiconductor nanorods toward enhanced near-infrared photoelectrochemical performance
摘要： Here we report a synthetic strategy for controllable construction of yolk-shell and core-shell plasmonic metal@semiconductor hybrid nanocrystals through modulating the kinetics of sulfurization reaction followed by cation exchange. The yielded yolk-shell structured products feature exceptional crystallinity and more importantly, the intimately adjoined and sharp interface between plasmonic metal and semiconductor which facilitates efficient charge carrier communications between them. By exploiting the system composed of Au nanorods and p-type PbS as a demonstration, we show that the Au@PbS yolk-shell nanorods manifest notable improvement in visible and near infrared light absorption compared to the Au@PbS core-shell nanorods as well as hollow PbS nanorods. Moreover, the photocathode constituted by Au@PbS yolk-shell nanorods affords the highest photoelectrochemical activities both under simulated sunlight and λ > 700 nm light irradiation. The superior performance of Au@PbS yolk-shell nanorods is considered arising from the combination of the favorable structural advantages of yolk-shell configuration and the surface plasmon resonance enhancement effect. We envision that the reported synthetic strategy can offer a valuable means to create hybrid nanocrystals with desirable structures and functions that enable to harness the photogenerated charge carriers, including the plasmonic hot holes, in wide-range solar-to-fuel conversion.
关键词： solar-to-fuel conversion,cation exchange,surface plasmon resonance,core-shell,yolk-shell
更新于2025-09-23 15:19:57
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Controlled Synthesis of Ag <sub/>2</sub> Te@Ag <sub/>2</sub> S Corea??Shell Quantum Dots with Enhanced and Tunable Fluorescence in the Second Neara??Infrared Window
摘要： Fluorescence in the second near-infrared window (NIR-II, 900–1700 nm) has drawn great interest for bioimaging, owing to its high tissue penetration depth and high spatiotemporal resolution. NIR-II fluorophores with high photoluminescence quantum yield (PLQY) and stability along with high biocompatibility are urgently pursued. In this work, a Ag-rich Ag2Te quantum dots (QDs) surface with sulfur source is successfully engineered to prepare a larger bandgap of Ag2S shell to passivate the Ag2Te core via a facile colloidal route, which greatly enhances the PLQY of Ag2Te QDs and significantly improves the stability of Ag2Te QDs. This strategy works well with different sized core Ag2Te QDs so that the NIR-II PL can be tuned in a wide range. In vivo imaging using the as-prepared Ag2Te@Ag2S QDs presents much higher spatial resolution images of organs and vascular structures as compared with the same dose of Ag2Te nanoprobes administrated, suggesting the success of the core–shell synthetic strategy and the potential biomedical applications of core–shell NIR-II nanoprobes.
关键词： NIR-II nanoprobes,Ag2Te@Ag2S,bioimaging,core–shell quantum dots
更新于2025-09-23 15:19:57
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Tailored Engineering of Bimetallic Plasmonic Au@Ag Core@Shell Nanoparticles
摘要： A distinctive synthetic method for the efficient synthesis of multifunctional bimetallic plasmonic Au@Ag core@shell nanoparticles (NPs) with tunable size, morphology, and localized surface plasmon resonance (LSPR) using Triton X-100/hexanol-1/deionized water/cyclohexane-based water-in-oil (W/O) microemulsion (ME) is described. The W/O ME acted as a “true nanoreactor” for the synthesis of Au@Ag core@shell NPs by providing a confined and controlled environment and suppressing the nucleation, growth, agglomeration, and aggregation of the NPs. High-resolution transmission electron microscopic analysis of the synthesized Au@Ag core@shell NPs revealed an “unusual core@shell” contrast, and the selected area electron diffraction and Moiré patterns showed that Au layers are paralleled to Ag layers, thus indicating the formation of Au@Ag core@shell NPs. Interestingly, the UV?visible spectrum of the Au@Ag core@shell NPs exhibited enthralling plasmonic properties by introducing a high-frequency quadrupolar LSPR mode originated from the isolated Au@Ag NPs along with a low-frequency dipolar LSPR mode originated from the coupled Au@Ag NPs. The effective plasmonic enhancement of the Au@Ag core@shell NPs is attributed to the extreme enhancement of the localized electromagnetic field by coupling of the localized surface plasmons of the Au core and Ag shell. The mechanisms for the nucleation and growth of Au@Ag core@shell NPs in W/O ME have been proposed. A unique electron transfer phenomenon between the Au core and Ag shell is elucidated for better understanding and manipulation of the electronic properties, which evinced the development of Au@Ag core@shell NPs through suppression of the galvanic replacement reaction.
关键词： localized surface plasmon resonance,Au@Ag core@shell,bimetallic plasmonic nanoparticles,electron transfer phenomenon,water-in-oil microemulsion
更新于2025-09-23 15:19:57
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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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Laser sintering of Cu@Ag core-shell nanoparticles for printed electronics applications
摘要： Bimetallic Cu@Ag core-shell nanoparticles (NPs) were synthesized by the reduction of copper 2-[2-(2-methoxyethoxy)ethoxy]acetate with hydrazine hydrate in benzyl alcohol followed by the reduction of silver ions on the copper surface using a galvanic replacement reaction. Ink consisting of the as-synthesized Cu@Ag NPs dispersed in a mixture of nontoxic solvents with different boiling temperatures (butanol and propylene glycol ethers) was prepared. Thin layers were spin coated on polyimide films using the developed ink. The conductive layer formed in air in the optimized conditions showed an electrical resistivity of 28.5 lX·cm.
关键词： Conductive inks,Laser sintering,Printed electronics,Copper,Core-shell nanoparticles,Silver
更新于2025-09-23 15:19:57
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Ge/Si Core/Shell Quantum Dots in an Alumina Matrix: Influence of the Annealing Temperature on the Optical Properties
摘要： Structures with Ge/Si nanoparticles (quantum dots) in an aluminum-oxide matrix are of interest due to the combination of two basic semiconductors and the use of a matrix with a high permittivity and strong oxygen–metal bonding. In this study, multilayer nanoperiodic structures in the form of a substrate/Al2O3/Ge/Si/Al2O3…Al2O3 sequence of layers (with the period Al2O3/Ge/Si and the number of periods up to 20) are produced and then annealed at different temperatures. It is shown that, after annealing, the structures contain both Ge and Si crystalline particles, whose dimensions and number are defined by the deposited-layer thicknesses and the annealing temperature. The results obtained by different optical techniques suggest that the structures exhibit the quantum-confinement effect. This inference is supported by high-resolution microscopy.
关键词： Ge/Si,multilayer nanostructures,core–shell quantum dots
更新于2025-09-23 15:19:57