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Extending Surface‐Enhanced Raman Spectroscopy to Liquids using Shell‐Isolated Plasmonic Superstructures
摘要： Plasmonic superstructures (PS) based on Au/SiO2 were prepared for Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) in liquid phase applications. These superstructures are composed of functionalized SiO2 spheres with plasmonic Au nanoparticles (NPs) on their surface. Functionalization was performed with (3-aminopropyl)-trimethoxysilane, and poly(ethylene-imine) (PEI). Of these three, PEI-functionalized spheres showed the highest adsorption density of Au NPs in TEM, UV/Vis and dynamic light scattering (DLS) experiments. Upon decreasing the Au NP/SiO2 sphere size ratio, an increase in adsorption density was also observed. To optimize plasmonic activity, 61 nm Au NPs were adsorbed onto 900 nm SiO2-PEI spheres and these PS were coated with an ultrathin layer (1–2 nm) of SiO2 to obtain Shell-Isolated Plasmonic Superstructures (SHIPS), preventing direct contact between Au NPs and the liquid medium. Zeta potential measurements, TEM and SHINERS showed that SiO2 coating was successful. The detection limit for SHINERS using SHIPS and a 638 nm laser was around 10?12 m of Rhodamine (10?15 m for uncoated PS), all with acquisition settings suitable for catalysis applications.
关键词： Raman spectroscopy,plasmonic nanoparticles,reaction monitoring,heterogeneous catalysis,SERS
更新于2025-09-19 17:13:59
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Plasmonic hybrid platinum-titania nanocomposites as highly active photocatalysts: self-cleaning of cotton fiber under solar light
摘要： In the present paper, a one-step, simple, efficient and low-cost strategy was demonstrated for preparing of highly stable hybrid platinum-titania (Pt@TiO2) photocatalyst by solvothermal wet chemical process. Platinum (Pt) in the metallic form combined with titania (TiO2) in the crystallographic anatase form has been manufactured using Dimethyl Sulfoxide (DMSO) as a solvent and surfactant using titanium (IV) butoxide and hydrogen hexachloroplatinate(IV) precursors. Full characterization of the hybrid nanomaterials including their morphology, crystalline structure and optical properties was determinate using different experimental techniques such as XRD, TEM and UV–vis spectroscopy. TEM images showed spherically shaped Pt nanoparticles (NPs) of the diameter 5–10 nm with good particle size distribution. The EDXRF data revealed that Pt NPs are in metallic form. Optical investigation show that Pt@TiO2 NPs exhibits a good optical response under UV–vis light excitation compared to bare-TiO2. Furthermore, photocatalytic investigation of Pt@TiO2 colloids photocatalyst towards the photodegradation of diuron, as a model organic pesticide was reported. The hybrid Pt@TiO2 photocatalyst prove high-performance on the photodecomposition of the pesticide under solar light within only 60 min. In the other hand, the plasmonic hybrid Pt@TiO2 was incorporated into the cotton fabric to attain a modified fiber with high self-cleaning activity.
关键词： Self-cleaning,Semiconductors,Heterogenous catalysis,Cotton fiber,Solvothermal method,Nanocomposites
更新于2025-09-16 10:30:52
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Pulsed laser synthesis of highly active Ag–Rh and Ag–Pt antenna–reactor-type plasmonic catalysts
摘要： Ag, Pt, and Rh monometallic colloids were produced via laser ablation. Separate Ag–Rh and Ag–Pt heterostructures were formed by mixing and resulted in groupings of Rh/Pt nanoparticles adsorbing to the concavities of the larger Ag nanostructures. The 400 nm Ag plasmonic absorption peak was slightly blue-shifted for Ag–Pt and red-shifted for Ag–Rh heterostructures. Catalytic activity for the reduction of 4-nitrophenol increased significantly for Ag–Pt and Ag–Rh compared to the monometallic constituents, and persisted at lower loading ratios and consecutive reduction cycles. The enhancement is attributed to the Rh and Pt nanoparticles forming antenna–reactor-type plasmonic catalysts with the Ag nanostructures.
关键词： Pt,catalysis,multicomponent,Rh,nanoparticles,antenna–reactor,4-nitrophenol,heterostructures,Ag,laser ablation,plasmonic
更新于2025-09-16 10:30:52
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Taking the Heat Off of Plasmonic Chemistry
摘要： Plasmon-excitation-mediated chemistry, which is a rapidly growing field, is founded on a simple principle: the excitation of the localized surface plasmon resonance (LSPR) of metal nanoparticles triggers chemical reactions on the surfaces of the nanoparticles. Early examples of plasmon-excitation-driven nanoparticle synthesis and hot-electron-driven chemical reactions induced by ultrashort pulse excitation of metal nanoparticles can be thought of as precursors to the findings of direct photocatalysis by plasmonic nanoparticles, which is the focus of this Viewpoint. The field in its current state was, in large part, invigorated by a 2011 paper, which showed that the excitation of the LSPR of Ag nanoparticles by continuous-wave (CW), visible-frequency light triggered the dissociation of adsorbed O2. The O· atoms thus produced were utilized for industrially relevant oxidation reactions such as those of propylene and ethylene, which would have otherwise required high-temperature and -pressure conditions to proceed at appreciable rates. In the absence of visible-light excitation, the bond dissociation and oxidation reactions proceeded at appreciably low rates, which indicated that plasmonic excitation enhanced the rates of these chemical reactions. The phenomenon is, therefore, termed as plasmonic catalysis or plasmonic photocatalysis.
关键词： Plasmonic catalysis,Plasmonic photocatalysis,Chemical reactions,Hot electrons,Photothermal heating
更新于2025-09-16 10:30:52
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External stimulus controlled recombination of hydrogen in photochromic dithienylethene frustrated lewis pairs
摘要： Photoswitchable catalysis involves changes in properties of a catalyst based on difference in electronic and steric factors. These changes can selectively turn "ON" and "OFF" the catalytic activity by an external stimulus, light. Herein, we report dithienylethene based photoswitchable frustrated Lewis pairs for facile hydrogen recombination. The diarylethene moiety is not serving as template to alter the catalytic activity rather it is the core part of the catalyst. The rational design principle involves study of proton and hydride affinities of Lewis acid and base functionalities installed on the diarylethene photoswitch pair. Proton and hydride affinities differ significantly between open and closed isomers that help in designing an active molecule for hydrogen recombination. The proton and hydride affinities are then utilized to formulate best relative positions of Lewis acid and base on a single molecule in order to liberate one H2 molecule per photochrome. Energy barriers for hydrogen recombination are calculated for open and closed isomers. The closed isomer releases the hydrogen with a low activation barrier of 1.9 kcal mol?1 whereas the open isomer requires relatively high barrier of 4.7 kcal mol?1. The pronounced differences in energy barrier illustrate the potential of photoswitchable hydrogen recombination with diarylethene photochrome. The chemically stored hydrogen in frustrated Lewis pairs can be liberated in a controlled fashion through external stimulus for catalytic hydrogenation reactions. The present study will provide new dimensions to the scientific community for exploration of other systems with even better selectivities.
关键词： Dithienylethene,Hydrogen recombination,Switchable catalysis,Frustrated lewis pairs
更新于2025-09-12 10:27:22
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Modulating Catalytic Performance of Metal-Organic Frameworks Composites by Localized Surface Plasmonic Resonance
摘要： Controlled integration of plasmonic nanoparticles with metal-organic frameworks (MOFs) creates a class of multifunctional nanomaterials that powerful for various applications, especially in the field of photocatalysis and photoelectrocatalysis -which recently have been witnessed a vast interest in the exploration of localized surface plasmon resonance of plasmonic NPs to improve the efficiency of catalysis processes. This perspective highlights and summarizes recent significant progress in the field of catalysis, focusing on integration strategies and considerations and several possible plasmonic enhancement mechanisms involved. Brief overviews of optical and electronics properties of plasmonic NPs is also introduced, and finally the development prospect of the field is briefly discussed.
关键词： Plasmonic nanoparticles,Metal-organic frameworks,LSPR,Catalysis,Composites
更新于2025-09-12 10:27:22
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Influence of Gamma-Irradiation on Structural, Optical and Photocatalytic Performance of TiO2 Nanoparticles Under Controlled Atmospheres
摘要： The effect of gamma-rays on structural, optical and photocatalytic properties of TiO2 nanoparticles under controlled atmospheres are studied to further improve photocatalytic performance. The sol–gel TiO2 powders were deposited with spin-coating technique, annealed at 500°C then finally irradiated by gamma-rays. The structural and optical characteristics of samples were investigated by Fourier transform infrared spectroscopy, x-ray diffraction and UV-visible spectroscopy (UV). The time-dependent density functional theory (TD-DFT) calculation are used to determine ground geometries and electronic structures of TiO2 nanostructures. DFT calculations present an excellent conformity with experimental results, and a high anisotropy in stretched thermal and electrical conductivity TiO2 nanostructures was found. Structural and optical results show that gamma radiation did not change the crystallinity of TiO2 nanostructures and leads to an optical band gap reduction to 3.039 eV. The gamma radiation effect on photocatalytic performance was investigated by methylene blue degradation as a typical pollutant. Gamma radiation has been discovered to improve considerably the degradation of pollutants compared with unirradiated TiO2.
关键词： optical properties,DFT,TiO2,Gamma ray radiation,photo catalysis
更新于2025-09-12 10:27:22
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Controlled joule-heating of suspended glassy carbon wires for localized chemical vapor deposition
摘要： This paper demonstrates for the first time localized chemical vapor deposition of WO3-x on a suspended glassy carbon wire. A process based on the photopatterning of an SU-8 scaffold, the near-field electrospinning of an SU-8 fiber, and their pyrolysis yields a monolithic carbon structure featuring a glassy carbon wire of known diameter and length, suspended on a glassy carbon scaffold. The temperature required for the deposition of WO3-x is generated by passing current through the wire, which causes Joule heating. The deposition starts in the midpoint of the wire, and extends to its ends as the current is increased. The thickness and length of the coating are functions of the imposed current. The evolution of the coating can be monitored in real time by measuring the voltage vs current characteristic of the wire. We have deposited WO3-x coatings with thickness from 71 nm to 1.4 μm, in glassy carbon wires with diameters between 780 nm and 2.95 μm. The coatings are uniform and polycrystalline. The suspended glassy carbon wire is a generic platform for the deposition of many transition metal oxide (TMO) coatings, and opens the door to carbon-TMO structures for applications including catalysis and gas sensing.
关键词： glassy carbon wire,gas sensing,localized chemical vapor deposition,WO3-x,catalysis,Joule heating,transition metal oxide
更新于2025-09-12 10:27:22
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Intermolecular [2+2] Carbonyl–Olefin Photocycloadditions Enabled by a Copper(I)–Norbornene Complex
摘要： Intermolecular [2+2] Carbonyl–Olefin Photocycloadditions Enabled by a Copper(I)–Norbornene Complex
关键词： oxetanes,metal-ligand charge transfer,copper catalysis,[2+2] carbonyl olefin photocycloaddition
更新于2025-09-12 10:27:22
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NiMo and NiW Nanostructured Catalysts of Thiophene Oxidation, Obtained via Laser Electrodispersion
摘要： New bimetallic catalysts based on Ni and Mo or W oxide nanoparticles deposited on alumina are obtained via the laser electrodispersion of tightly compacted binary mixtures of NiMo and NiW powders. SEM, TEM, and XPS show that both components of each pair are uniformly distributed over a carrier’s surface in the form of nanoparticles of 4–7 nm in size. Metals on the catalyst’s surface are predominantly in an oxidized state. The catalytic activity of NiMo/Al2O3 and NiW/Al2O3 pairs is compared using examples of the oxidation of thiophene and dibenzothiophene with hydrogen peroxide. High reagent conversion on such catalysts with ultra-low metal contents (<0.01 wt %) is maintained by continually repeating the process. Introducing a zwitterionic liquid with sulfo group into the reaction mixture results in additional improvement of catalyst efficiency.
关键词： oxidation,thiophene,laser electrodispersion,catalysis,nanoparticles
更新于2025-09-12 10:27:22