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KMnF3:Yb3+,Er3+ Core-Active-Shell Nanoparticles with Broadband Down-Shifting Luminescence at 1.5 μm for Polymer-Based Waveguide Amplifiers
摘要： In this study, we prepared cubic-phase oleic-acid-coated KMnF3: Yb3+,Er3+ nanoparticles (NPs) and NaYF4:Yb3+,Er3+ NPs, which were about 23 nm. From the down-shifting emissions spectra of the two NPs obtained by 980 nm excitation, we observed the fact that the KMnF3: 18%Yb3+,1%Er3+ NPs were a luminescent material with a broadband near-infrared emission of 1.5 μm, and full-width at half-maximum (FWHM) of 55 cm?1, which was wider than that of the NaYF4: 18%Yb3+,1% NPs. Therefore, we believe that the oleic-acid-coated KMnF3:Yb3+,Er3+ NPs have great potential in fabricating broadband waveguide ampli?ers. Through epitaxial growth of a KMnF3: Yb3+ active-shell on the core NPs, we compounded KMnF3:Yb3+,Er3+@KMnF3:Yb3+ core-active-shell NPs whose 1.5-μm infrared emissions intensity was 3.4 times as strong as that of the core NPs. In addition, we manufactured waveguide ampli?ers using KMnF3:18%Yb3+,1%Er3+@KMnF3:2%Yb3+ NPs as the core materials of the waveguide ampli?ers. When the input signal power was 0.2 mW and the pump power was 200 mW, we achieved a relative gain of 0.6 dB at 1534 nm in a 10-mm long waveguide.
关键词： broadband,1.5 μm,KMnF3:Yb3+,Er3+ core-shell nanoparticles,polymer-based waveguide ampli?ers,down-shifting luminescence
更新于2025-11-14 15:27:09
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One-step fabrication of effective mesoporous layer consisted of self-assembled MgO/TiO<sub>2</sub> core/shell nanoparticles for mesostructured perovskite solar cells
摘要： perovskite directly, which can not only passivate surface defects and reduce charge-suppressed J-V hysteresis. Meanwhile, the photovoltaic characteristics and the well-power conversion efficiency (PCE) was increased from 13.13% to 16.30% with well-interface and electrons transfer in PSCs. Based on the mesoporous layer consisting of nanoparticles instead of adding an additional surface modified layer for mesostructured recombination, but also facilitate charge-extraction at the mesoporous layer/perovskite perovskite solar cells (PSCs). An amorphous ultrathin outer nanolayer of MgO was Such self-assembled MgO/TiO2 core/shell nanostructures would retain the mesoporous of PSCs was 1.00 V, 4.2% higher than the uncoated TiO2 based PSCs, and the obtained structure feature, supply more contact interface of MgO/TiO2 and separate the TiO2 and conformally coated onto TiO2 core nanoparticles in a one-step bottom-up approach. proposed an efficient nanoparticulate mesoporous layer consisted of coated TiO2 optimized MgO-coated TiO2 nanoparticles, the corresponding open circuit voltage (VOC) Considering the intrinsic rich defect, poor H2O or UV light stability of TiO2, we resistance is obtained for the cell based on m-TiO2 with MgO coating. In addition, we behaved junction property were further clarified by the ideal model, a much lower series provided an easy regulated uniform coating route to fabricate well-defined core-shell nanoparticles with modified properties.
关键词： Uniform coating,mesoporous layer,Core-shell nanostructure,Perovskite solar cells
更新于2025-11-14 15:27:09
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Significantly Enhanced Energy Density by Tailoring the Interface in a Hierarchical-Structured TiO2-BaTiO3-TiO2 Nanofillers in PVDF Based Thin Film Polymer Nanocomposite
摘要： Dielectric polymer nanocomposites with high breakdown field and high dielectric constant have drawn significant attention in modern electrical and electronic industries due to their potential applications in dielectric and energy storage systems. The interfaces of the nanomaterials play a significant role in improving the dielectric performance of polymer nanocomposites. In this work, polydopamine (dopa) functionalized TiO2-BaTiO3-TiO2 (TiO2-BT-TiO2@dopa) core@double-shell nanoparticles have been developed as novel nanofillers for high energy density capacitor application. The hierarchically designed nanofillers help in tailoring the interfaces surrounding the polymer matrix as well as act as individual capacitors in which core and outer TiO2 shell functions as capacitor plate because of their high electrical conductivity while the middle BT layer functions as a dielectric medium due to high dielectric constant. Detailed electrical characterizations have revealed that TiO2-BT-TiO2@dopa/PVDF possess maximum relative dielectric permittivity (εr), breakdown strength (Eb), as well as energy densities in comparison to PVDF, TiO2/PVDF, TiO2@dopa/PVDF, TiO2-BT@dopa/PVDF polymer nanocomposites. The εr and energy density of TiO2-BT-TiO2@dopa/PVDF was 12.6 at 1 kHz and 4.4 J cm-3 at 3128 kV cm-1, respectively, which was comparatively much higher than commercially available biaxially oriented polypropylene (BOPP) having εr of 2.2 and the energy density of 1.2 J cm-3 at much higher electric field of 6400 kV cm-1. It is expected that these results will further open new avenues for the design of novel architecture for high-performance polymer nanocomposites-based capacitors having core@multishell nanofillers with tailored interfaces.
关键词： capacitors,polymer nanocomposites,core-shell nanomaterials,dielectrics,BaTiO3 nanoparticles
更新于2025-11-14 15:19:41
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How to unravel the chemical structure and component localization of individual drug-loaded polymeric nanoparticles by using tapping AFM-IR
摘要： AFM-IR is a photothermal technique that combines AFM and infrared (IR) spectroscopy to unambiguously identify the chemical composition of a sample with tens of nanometer spatial resolution. So far, it has been successfully used in contact mode in a variety of applications. However, the contact mode is unsuitable for soft or loosely adhesive samples such as polymeric nanoparticles (NPs) of less than 200 nm of wide interest for biomedical applications. We describe here the theoretical basis of the innovative tapping AFM-IR mode that can address novel challenges in imaging and chemical mapping. The new method enables gaining information not only on NP morphology and composition, but also reveals drug location and core–shell structures. Whereas up to now the locations of NP components could only be hypothesized, tapping AFM-IR allows accurately visualizing both the location of the NPs’ shells and that of the incorporated drug, pipemidic acid. The preferential accumulation of the drug in the NPs’ top layers was proved, despite its low concentration (<1 wt%). These studies pave the way towards the use of tapping AFM-IR as a powerful tool to control the quality of NP formulations based on individual NP detection and component quantification.
关键词： tapping mode,chemical mapping,core–shell structure,drug localization,polymeric nanoparticles,AFM-IR
更新于2025-11-14 15:18:02
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TiO2-Coated Core-Shell Ag Nanowire Networks for Robust and Washable Flexible Transparent Electrodes
摘要： Silver nanowires (AgNWs) are the most promising materials to fabricate flexible transparent electrodes (FTEs) used in next-generation electronics. However, there are several bottlenecks for AgNWs-based FTEs to achieve large-scale applications, which are the thermal instability and rough surface topography of AgNWs and the poor interfacial adhesion between AgNWs and used substrate. To simultaneously address these aforementioned issues, a robust and washable FTE is prepared based on AgNW@TiO2 core-shell network embedding in polyimide (PI) substrate through a facile and scalable solution-based process. After treating with TiO2 sol, an ultra-thin, conformal, and continuous TiO2 shell is coated on AgNWs, which can effectively suppress the atomic surface diffusion. In comparison with pristine AgNW network that breaks into nanorods and nanospheres at 250 °C for 10 min, the AgNW@TiO2 core-shell network is stable at 300 °C, and its resistance just increases by a factor of 11 after annealing at 400 °C for 1 h. Furthermore, the TiO2 shell simultaneously increases the electrical and optical properties of AgNW network. After flowing PI precursors, drying, and thermally curing, the AgNW@TiO2 core-shell network is embedded on the surface of PI substrate with surface roughness of 1.9 nm. In addition to high thermal stability, the conductivity of the AgNWs@TiO2-PI composite FTE remains almost unchanged after repeated 3M tape peeling off cycles and mechanical bending cycles. It is also demonstrated that the AgNWs@TiO2-PI composite FTE is washable, and the relative change in resistance (?R/R0) is ~12% after 100 washing cycles in which a variety of stress situations occurring in combination.
关键词： flexible transparent electrodes,peeling off and mechanical stabilities,TiO2 sol,silver nanowire@TiO2 core-shell network,thermal and washing stabilities
更新于2025-11-14 14:32:36
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Giant-Shell CdSe/CdS Nanocrystals: Exciton Coupling to Shell Phonons Investigated by Resonant Raman Spectroscopy
摘要： The interaction between excitons and phonons in semiconductor nanocrystals plays a crucial role in the exciton energy spectrum and dynamics, and thus in their optical properties. We investigate the exciton-phonon coupling in giant-shell CdSe/CdS core-shell nanocrystals via resonant Raman spectroscopy. The Huang-Rhys parameter is evaluated by the intensity ratio of the longitudinal-optical (LO) phonon of CdS with its first multiscattering (2LO) replica. We used four different excitation wavelengths in the range from the onset of the CdS shell absorption to well above the CdS shell band edge to get insight into resonance effects of the CdS LO phonon with high energy excitonic transitions. The isotropic spherical giant-shell nanocrystals show consistently stronger exciton-phonon coupling as compared to the anisotropic rod-shaped dot-in-rod (DiR) architecture, and the 2LO/LO intensity ratio decreases for excitation wavelengths approaching the CdS band edge. The strong exciton-phonon coupling in the spherical giant-shell nanocrystals can be related to the delocalization of the electronic wave functions. Furthermore, we observe the radial breathing modes of the GS nanocrystals and their overtones by ultra-low frequency Raman spectroscopy with nonresonant excitation, using laser energies well below the band gap of the heteronanocrystals, and highlight the differences between higher order optical and acoustic phonon modes.
关键词： Giant-shell nanocrystals,acoustic phonons,Dot-in-rods,Raman spectroscopy,Core-shell heterostructures,exciton-phonon coupling
更新于2025-09-23 15:23:52
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Enhanced sensor life using UV treatment of sulphur poisoned Pt-PtOx
摘要： In this work, we report a novel method for recovery of sulphur poisoned platinum/platinum oxide (Pt-PtOx) core-shell nanowire sensor using UV irradiation. The optimum core to shell thickness ratio and the operating conditions are the key factors to achieve a high-performance H2S sensor, described in this report. The fabricated core-shell nanowire sensor demonstrated response of 6.4% at 1 ppm H2S with detection limit of 10 ppb at 150°C operating temperature. The sensor undergoes prominent time-dependent poisoning at H2S exposure of 3 ppm when operated at 150°C due to sensor surface contamination by sulphur, later confirmed by XPS analysis. Ultraviolet light at two wavelengths, 365 nm, and 248 nm is investigated to recover the poisoned Pt-PtOx surface. UV irradiation at 248 nm for 5 minutes results in sensor recovery, confirmed by further H2S sensing characterization and XPS studies on the recovered sensor. To the best of our knowledge, this is one of the first reports on UV irradiation for recovery of sulphur poisoned metal-oxide surfaces.
关键词： sulphidation,recovery,plasma oxidation,UV irradiation,core-shell nanowire
更新于2025-09-23 15:23:52
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Efficient near-infrared photocatalysts based on NaYF4:Yb3+,Tm3+@NaYF4:Yb3+,Nd3+@TiO2 core@shell nanoparticles
摘要： In this work, we fabricated NaYF4:Yb3+,Tm3+@NaYF4:Yb3+,Nd3+@TiO2 (Tm@Nd@TiO2) core@shell nanoparticles and investigated their near-infrared (NIR) photocatalytic activities. Comparing to traditional TiO2 based upconversion (UC) photocatalysts (i.e., NaYF4:Yb3+,Tm3+@TiO2, named Tm@TiO2), Tm@Nd@TiO2 exhibits enhanced photocatalytic activity under NIR light irradiation. The photocatalytic activity of Tm@Nd@TiO2 under 980, 808, and 980+808 nm laser irradiation is 4.40, 5.84, and 9.83 times as high as that of Tm@TiO2 under only 980 nm irradiation, respectively. The ethylene degradation rate of Tm@Nd@TiO2 under 980+808 nm laser irradiation is 6.4 times as that of Tm@TiO2. The photocatalytic activity of Tm@Nd@TiO2 under visible+NIR irradiation is even comparable with (~2/3) that under UV light irradiation during Rhodamine B (RhB) degradation. The enhanced photocatalytic activity of Tm@Nd@TiO2 can be attributed to the stronger light absorption in NIR region ascribed to Nd3+, lower water absorption and the enhanced UC emission of Tm@Nd with unique core@shell nanostructures. This work can provide a possible route to improve the NIR photocatalytic activity and stimulate the applications in many other fields.
关键词： upconversion,near-infrared irradiation,photocatalyst,core@shell structure
更新于2025-09-23 15:23:52
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Nano-BaTiO3 phase transition behavior in coated BaTiO3-based dielectric ceramics
摘要： In this work, the phase structure of BaTiO3 nanopowders produced by the alkoxide-hydroxide and the hydrothermal method, respectively, was systemically investigated. BaTiO3 nanopowders with cubic phase produced by the alkoxide-hydroxide method could transform to tetragonal phase when heated to about 1100oC. Cubic to tetragonal phase transformation behavior of BaTiO3 nanopowders coated with 0.3BZT-0.7BT or 0.03Nb2O5-0.01Co2O3 was studied. The internal stress within core-shell structure was proposed to explain the BaTiO3 phase transformation behaviors. The mismatch of thermal expansion coefficient between core and shell plays a crucial role in cubic to tetragonal phase transformation of BaTiO3. By tuning the composition of shell and the ratio of the shell to the core, the cubic BaTiO3 core can transform to tetragonal phase successfully after sintering at 1100oC in BaTiO3 based ceramics with core-shell structure and it is mainly resulted by the reduced internal stress between the shell and core.
关键词： Phase transitions,BaTiO3 nanopowders,Internal stress.,Core-shell structure
更新于2025-09-23 15:23:52
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Single-Crystal ZnO/AlN Core/Shell Nanowires for Ultraviolet Emission and Dual-Color Ultraviolet Photodetection
摘要： Core–shell nanostructures can combine the advantages of different functional materials to realize property tunability and enhance optical and optoelectrical performance. Here, vertically aligned ZnO/AlN core/shell nanowires have been facilely fabricated by sputtering AlN layer onto the ZnO nanowires grown by vapor phase transport. The morphological and structural characterization reveals that single-crystal AlN shell layer with thickness of ≈15 nm is coated uniformly on the single-crystal ZnO nanowire with diameters of ≈330 nm. The core/shell nanowire exhibits 24 times enhancement of ultraviolet emission and quenching of the deep level emission from ZnO. Moreover, under ultraviolet irradiation (325 nm), the photodetector based on the core/shell nanowire displays higher photoresponsivity (from 3.8 × 103 to 2.05 × 104 A W?1), faster response speed (from 397 to 28 ms), and higher I325nm/Idark ratio (from 453 to 1.1 × 104) than that bare ZnO nanowire device. Under the vacuum ultraviolet (193 nm) illumination, the I193nm/Idark ratio and photoresponsivity are 300 and 381 A W?1, respectively. In one word, this paper employs a facile and general technique to solve a challenging fabrication issue, and obtains perfect crystal core/shell structure with high performance for ultraviolet emission and detection.
关键词： single-crystal core/shell,AlN,ZnO nanowires,ultraviolet emission,dual-color ultraviolet photodetection
更新于2025-09-23 15:23:52