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Ultrathin and Isotropic Metal Sulfide Wrapping on Plasmonic Metal Nanoparticles for SERS-based Detection of Trace Heavy Metal Ions.
摘要： A facile and general strategy is presented for homogenous and ultrathin metal sulfide-wrapping on plasmonic metal (PM) nanoparticles (NPs) based on a thiourea-induced isotropic shell growth. This strategy is typically implemented just via adding the thiourea into pre-formed PM colloidal solutions containing target metal ions. The validity of this strategy is demonstrated by taking the wrapped NPs with Au core and CuS shell or Au@CuS NPs as an example. They are successfully fabricated via adding the thiourea and Cu2+ solutions into pre-formed Au NP colloidal solution. The CuS shell layer is highly homogenous (<10% in relative standard deviation of shell thickness), regardless of the NPs’ shape or curvature. The shell thickness can be controlled from tens down to 0.5 nm just by the addition amounts of the shell precursors. The formation of the shell layer on the Au NPs can be attributed to the alternative deposition of Cu2+ and S2- ions on the thiourea-modified surface of Au NPs in the solution, which induces the isotropic shell growth. Further, this strategy is of good universality. Many other sulfide-wrapped PM NPs, such as Ag@CuS, Au@PtS2, Au@HgS, Ag@Ag2S NPs and Ag@CuS nanorods have been successfully obtained with homogeneous and ultrathin shells. Importantly, such ultrathin sulfide-wrapped PM NPs can be used for SERS-based detection of trace heavy metal ions with strong anti-interference via ion exchange process between the metal sulfide shell and heavy metal ions. This study provides a simple and controllable route for wrapping the homogenous and ultrathin sulfide layers on the PM NPs, and such wrapped NPs have good practical applications in the SERS-based detection of trace heavy metal ions.
关键词： Plasmonic metal nanoparticles,Trace heavy metal ions,Ultrathin sulfide wrapping,Thiourea-induced isotropic shell growth,SERS-based detection
更新于2025-11-14 17:04:02
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Unravelling the effect of charge dynamics at the plasmonic metal/semiconductor interface for CO2 photoreduction
摘要： Sunlight plays a critical role in the development of emerging sustainable energy conversion and storage technologies. Light-induced CO2 reduction by artificial photosynthesis is one of the cornerstones to produce renewable fuels and environmentally friendly chemicals. Interface interactions between plasmonic metal nanoparticles and semiconductors exhibit improved photoactivities under a wide range of the solar spectrum. However, the photo-induced charge transfer processes and their influence on photocatalysis with these materials are still under debate, mainly due to the complexity of the involved routes occurring at different timescales. Here, we use a combination of advanced in situ and time-resolved spectroscopies covering different timescales, combined with theoretical calculations, to unravel the overall mechanism of photocatalytic CO2 reduction by Ag/TiO2 catalysts. Our findings provide evidence of the key factors determining the enhancement of photoactivity under ultraviolet and visible irradiation, which have important implications for the design of solar energy conversion materials.
关键词： Ag/TiO2 catalysts,photocatalysis,plasmonic metal nanoparticles,sustainable energy,solar energy conversion,artificial photosynthesis
更新于2025-10-22 19:40:53
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Probing the Advantageous Photosensitization Effect of Metal Nanoclusters over Plasmonic Metal Nanocrystals in Photoelectrochemical Water Splitting
摘要： Atomically precise metal nanoclusters (NCs)-based photocatalytic systems have garnered enormous attention owing to the fascinating merits including unique physicochemical properties, quantum confinement effect and photosensitization effect, which are distinct from conventional metal nanocrystals (NYs). Nevertheless, systematic comparison between electrons photoexcited from metal NCs and hot electrons from surface plasmonic resonance (SPR) effect of metal NYs in boosting photoelectrochemical water splitting reaction remains blank. Here, we report the strict and comprehensive comparison on the capability of electrons photoexcited from glutathione-capped gold nanoclusters (Aux@GSH) and hot electrons from plasmonic excitation of gold nanoparticles (Au NYs) self-transformed from Aux@GSH to trigger the PEC water splitting reaction under visible light irradiation. The results indicate photoelectrons of Aux NCs trigger more efficient charge transport rate than hot electrons of plasmonic Au NYs in terms of light harvesting and conversion efficiency under the identical conditions. Moreover, charge transfer characteristics in Aux NCs and Au NYs-based PEC systems were established. This work would reinforce our deep understanding on these two pivotal sectors of metal nanomaterials for solar energy conversion.
关键词： photosensitization effect,plasmonic metal nanocrystals,charge transfer,photoelectrochemical water splitting,metal nanoclusters
更新于2025-09-23 15:19:57
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SPR studies on optical fiber coated with different plasmonic metals for fabrication of efficient biosensors
摘要： In the recent years, there have been numerous reports on study of Surface Plasmon Resonance (SPR) in different Plasmonic metals. Optical – fiber based SPR sensors have gained much attention over the years because of their copious advantages over conventional Prism coupled SPR sensors, including miniaturization, ability to perform remote sensing etc. In the present work, Optical – fiber based Surface Plasmon studies are performed on metal – air interface with different Plasmonic metals. Four different metals chosen for the current work are as follows: Gold (Au), Silver (Ag), Aluminum (Al) and Copper (Cu). Thermal Evaporation technique is utilized to deposit the Au, Ag, Al and Cu metal thin films. XRD, AFM and UV–Visible spectroscopy are used for the determination of the structural, morphological and optical characteristics of the deposited metal thin films. SPR transmittance curve is obtained for different metals and their observed SPR wavelength (kspr) matches very well with the reported values. The performance of these metals for their application in SPR based biosensors, was assessed in terms of the Full Width at Half Maxima (FWHM) and minimum transmitted intensity (Tmin) of their SPR transmittance curves and it was found that Ag (50 nm thickness) possesses the least FWHM whereas Au (40 nm thickness) has the lowest Tmin. Suitability of both Ag and Au is discussed for sensing applications and it was concluded that Au (40 nm thickness) is a better candidate for the realization of efficient biosensors.
关键词： SPR,Plasmonic metal,FWHM,Optical fiber,Bio sensor
更新于2025-09-23 15:19:57
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Interaction of ZnO nanorods with plasmonic metal nanoparticles and semiconductor quantum dots
摘要： We model the enhancement of near band edge emission from ZnO nanorods using plasmonic metal nanoparticles and compare it with emission enhancement from ZnO with semiconducting quantum dots. Selected CdSe quantum dots with absorption energies close to those of Ag and Au nanoparticles are chosen to construct model systems with ZnO to comprehend the role of ZnO’s intrinsic defects and plasmonic excitation in realizing the spectrally selective luminescence enhancement. Excitation wavelength dependent photoluminescence spectra along with theoretical models quantifying the related transitions and plasmonic absorption reveal that a complex mechanism of charge transfer between the ZnO nanorods and metal nanoparticles or quantum dots is essential along with an optimal energy band alignment for realizing emission enhancement. The theoretical model presented also provides a direct method of quantifying the relative transition rate constants associated with various electronic transitions in ZnO and their change upon the incorporation of plasmonic nanoparticles. The results indicate that, while the presence of deep level defect states may facilitate the essential charge transfer process between ZnO and the plasmonic nanoparticles, their presence alone does not guarantee UV emission enhancement and strong plasmonic coupling between the two systems. The results offer clues to designing novel multicomponent systems with coupled plasmonic and charge transfer effects for applications in charge localization, energy harvesting, and luminescence enhancement, especially in electrically triggered nanophotonic applications.
关键词： ZnO nanorods,plasmonic metal nanoparticles,semiconductor quantum dots,luminescence enhancement,charge transfer
更新于2025-09-23 15:19:57
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Plasmonic Switching of the Reaction Pathway: Visible‐Light Irradiation Varies the Reactant Concentration at the Solid–Solution Interface of a Gold–Cobalt Catalyst
摘要： Product selectivity of alkyne hydroamination over catalytic Au2Co alloy nanoparticles (NPs) can be made switchable by a light-on/light-off process, yielding imine (cross-coupling product of aniline and alkyne) under visible-light irradiation, but 1,4-diphenylbutadiyne in the dark. The low-flux light irradiation concentrates aniline on the catalyst, accelerating the catalytic cross-coupling by several orders of magnitude even at a very low overall aniline concentrations (1.0 X 10@3 mol L@1). A tentative mechanism is that Au2Co NPs absorb light, generating an intense fringing electromagnetic field and hot electrons. The sharp field-gradient (plasmonic optical force) can selectively enhance adsorption of light-polarizable aniline molecules on the catalyst. The light irradiation thereby alters the aniline/alkyne ratio at the NPs surface, switching product selectivity. This represents a new paradigm to modify a catalysis process by light.
关键词： product selectivity,reaction pathway,selective adsorption,visible-light photocatalysis,plasmonic metal nanoparticles
更新于2025-09-19 17:13:59
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Plasmonic Cu Nanostructures in ZnO as Hyperbolic Metamaterial Thin Films
摘要： Plasmonic metals, such as Cu and Al, have been considered as potential low-loss alternatives for Au and Ag for photonic structures and devices. However challenges remain in the fabrication and applications of Cu nanostructures, due to its easy oxidation issues. In this work, a new metamaterial structure of plasmonic Cu nanostructures embedded in a dielectric ZnO matrix has been designed and successfully fabricated using a one-step thin film growth method. The Cu-ZnO hybrid thin films present excellent epitaxial quality and exotic optical properties, such as strong localized surface plasmon resonance in the visible regime, and, highly anisotropic and hyperbolic optical response, revealed by angular dependent and polarization resolved reflectivity measurements. This hyperbolic plasmonic metamaterial via the metal-in-oxide matrix form combining low loss plasmonic Cu nanostructures and extraordinary anisotropic optical properties could be used towards various nanophotonic applications, such as plasmonic solar energy devices and hyperlens.
关键词： anisotropic optical property,Cu nanorods,metamaterial,self-assembled,low-loss plasmonic metal
更新于2025-09-11 14:15:04