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Ultrafast electron-lattice thermalization in copper and other noble metal nanoparticles
摘要： Using time-resolved ultrafast pump-probe spectroscopy we investigated the electron-lattice energy transfer in small copper nanospheres with diameters ranging from 3.2 to 23 nm, either embedded in a glass or dispersed in a solvent. Electron-lattice scattering rate is shown to increase with size reduction, in agreement with our previous results obtained on gold and silver nanoparticles in the low excitation regime. We attribute this effect to the reduction of the screening efficiency of electron–phonon interactions close to the nanoparticle surface. To understand the discrepancy between the results on the electron-lattice scattering in different metals reported in the literature (reduction, no dependence or increase with nanoparticle size), we discuss the experimental conditions required for the accurate determination of electron-lattice energy transfer time from time-resolved investigations in the weak and strong excitation regimes and present power-dependent experiments on gold nanospheres in solution. Our findings are derived from a theoretical analysis based on the two-temperature model predictions and on a complete modeling of the nanoparticle transient extinction cross-section through the resolution of Boltzmann equation in the presence of hot electrons.
关键词： pump-probe spectroscopy,copper nanoparticles,electron-lattice interactions,two-temperature model,ultrafast electron dynamics
更新于2025-09-23 15:23:52
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Tunable Localized Surface Plasmon Resonance and Broadband Visible Photo-response of Cu Nanoparticles/ZnO Surfaces
摘要： Plasmonic Cu nanoparticles (NP) were successfully deposited on ZnO substrates by atomic layer deposition (ALD) owing to the Volmer–Weber island growth mode. An evolution from Cu NP to continuous Cu films was observed with increasing the number of ALD cycles. Real and imaginary parts of the NP dielectric functions, determined by spectroscopic ellipsometry using an effective medium approach, evidence a localized surface plasmon resonance that can be tuned between the visible and near infrared ranges by controlling the interparticle spacing and size of the NP. The resulting Cu NP/ ZnO device shows an enhanced photo-response under white light illumination with good responsivity values, fast response times and stability under dark/light cycles. The significant photocurrent detected for this device is related with the hot electron generation at the NP surface and injection into the conduction band of the ZnO. The possibility of tuning the plasmon resonance together with the photo-responsivity of the device is promising in many applications related with photo-detection, photonics and photovoltaics.
关键词： atomic layer deposition,hot electrons,copper nanoparticles,photodetectors,localized surface plasmon resonance
更新于2025-09-23 15:21:01
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Temperature Dependent Spectroscopic Properties of Cu <sup>+</sup> and Dy <sup>3+</sup> Co-Doped Phosphate Glass: Band Gap Analysis and Cu Nanocluster-Enhanced Dy <sup>3+</sup> Luminescence
摘要： This paper reports on the effects of temperature on light absorption and emission in Cu + and Dy3 + co-doped phosphate glass, which is of interest for photonic applications. First, the temperature dependence of the absorption edge of the glass in connection with Cu + ions absorption was assessed. A thermally-induced red shift attributed to Cu + ion-lattice interactions was observed and analyzed through optical band gap determinations in the context of indirect-allowed transitions. Application of the Varshni model for the dependence of the energy gaps with temperature allowed to estimate the 0 K energy gap at 2.87 (? 0.01) eV. Furthermore, Dy3 + photoluminescence (PL) along with Cu nanoparticles (NPs) absorption was monitored in real-time during an isothermal treatment by the in situ concurrent PL and absorption microspectroscopy technique. Periods of enhancement and quenching of Dy3 + emission linked to bidirectional energy transfer processes involving non-plasmonic Cu clusters and plasmonic Cu NPs were revealed. The formation of Cu NPs was promoted by tin(II) used as reductant. It is the first time to the author’s knowledge that the 0 K energy gap is estimated for a highly Cu +-doped glass and that the enhancement of Dy3 + PL by Cu clusters is exposed.
关键词： rare earths,glasses,luminescence,copper,nanoparticles
更新于2025-09-23 15:19:57
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Enhancement of the fluorescence properties of double stranded DNA templated copper nanoparticles
摘要： The weak fluorescence emission from dsDNA templated copper nanoparticles necessitates the use of high-end detectors like photomultiplier tubes for their detection. This sets limitations on their applicability to in-situ analyte detection and point-of-care applications which utilize comparatively low cost and less sensitive detectors. In this article, a technique to improve the fluorescence properties of copper nanoparticles templated on dsDNA is reported. The fluorescence enhancement is achieved by introducing a modification in the conventional synthesis technique by using a combination of sodium ascorbate and Taq buffer. When compared to the existing methods, the proposed method achieves 11 times higher fluorescence signal intensity from the dsDNA templated copper nanoparticles and 4 times faster attainment of maximum fluorescence signal. The effect of the ionic strength of the individual constituent components of Taq buffer on the fluorescence emission from the copper nanoparticles is also studied here. The utility of this enhancement strategy for analyte measurement is demonstrated with the example of melamine detection from milk samples. A linear relationship was observed between the fluorescence intensity from the copper nanoparticles and the concentration of melamine in the range from 0.5 ppm to 100 ppm (R2 = 0.9919), with a limit of detection of 0.1 ppm. The reported fluorescence enhancement technique also results in 2.95 times improved sensitivity of detection when compared to the conventional technique.
关键词： dsDNA templated copper nanoparticles,Melamine detection
更新于2025-09-19 17:15:36
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Fabrication and Deposition of Copper and Copper Oxide Nanoparticles by Laser Ablation in Open Air
摘要： The proximity of the “post-antibiotic era”, where infections and minor injuries could be a cause of death, there are urges to seek an alternative for the cure of infectious diseases. Copper nanoparticles and their huge potential as a bactericidal agent could be a solution. In this work, Cu and Cu oxide nanoparticles were synthesized by laser ablation in open air and in argon atmosphere using 532 and 1064 nm radiation generated by nanosecond and picosecond Nd:YVO4 lasers, respectively, to be directly deposited onto Ti substrates. Size, morphology, composition and the crystalline structure of the produced nanoparticles have been studied by the means of field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), the energy dispersive spectroscopy of X-rays (EDS), selected area electron diffraction (SAED) and X-ray diffraction (XRD). The UV-VIS absorbance of the thin layer of nanoparticles was also measured, and the antibacterial capacity of the obtained deposits tested against Staphylococcus aureus. The obtained deposits consisted of porous coatings composed of copper and copper oxide nanoparticles interconnected to form chain-like aggregates. The use of the argon atmosphere contributed to reduce significantly the formation of Cu oxide species. The synthesized and deposited nanoparticles exhibited an inhibitory effect upon S. aureus.
关键词： copper nanoparticles,laser ablation,antibacterial effects
更新于2025-09-19 17:13:59
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Synthesis of graphene quantum dots stabilized CuNPs and their applications in CuAAC reaction and 4-nitrophenol reduction
摘要： Here we report the synthesis of graphene quantum dots (GQDs) stabilized copper nanoparticles in neat water. Construction of six CuNPs 1-6 nanocomposites are accomplished by mixing GQDs and NaBH4, and followed by the addition of different amounts of copper sulfate at 0 ℃ in water, respectively. Among them, CuNP-3, with the size of 2.6 nm, exhibits excellent catalytic performance in the CuAAC reaction over than other CuNPs. Moreover, the CuNP-3 has also been successfully applied for the reduction of 4-nitrophenol with excellent catalytic activity.
关键词： 4-Nitrophenol reduction,Copper nanoparticles,CuAAC reaction,Graphene quantum dots
更新于2025-09-19 17:13:59
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On the comparable activity in plasmonic photocatalytic and thermocatalytic oxidative homocoupling of alkynes over prereduced copper ferrite
摘要： Despite of extensive attention on the copper-based heterogeneous oxidative homocoupling of alkynes (OHA) to 1,3-diynes, the photocatalytic OHA is scarcely investigated. By screening copper-containing spinel catalysts, we discovered that a prereduced copper ferrite (CuFe2O4) not only can catalyze the thermocatalytic OHA but also is efficient for the photocatalytic OHA under visible light irradiation. It is found that the sol-gel combustion (SG) method and the partial reduction at 250 oC can result in the optimal CuFe2O4-SG-250 catalyst showing high activity and stability. Surface oxidized Cu2O is evidenced to be the active species for the thermocatalytic OHA, whereas metallic copper nanopaticles (CuNPs) are identified as the active sites for the photocatalytic OHA. The efficiency of photocatalytic OHA at ambient temperature is comparable to that of thermocatalytic OHA at 120 oC, and the CuFe2O4-SG-250 catalyst can be magnetically separated and reused at least five times. The localized surface plasmon resonance effect of CuNPs contributes to visible light-induced photocatalytic OHA.
关键词： Surface plasmon resonance,Alkyne,Homocoupling,Copper ferrite,Copper nanoparticles
更新于2025-09-16 10:30:52
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Laser sintering of Cu nanoparticles on PET polymer substrate for printed electronics at different wavelengths and process conditions
摘要： This study explores the feasibility of different laser systems to sinter screen-printed lines from non-conductive copper nanoparticles (Cu NPs) on polyethylene terephthalate polymer film. These materials are commonly used in manufacturing functional printed electronics for large-area applications. Here, optical and thermal characterization of the materials is conducted to identify suitable laser sources and process conditions. Direct diode (808 nm), Nd:YAG (1064 nm and second harmonic of 532 nm), and ytterbium fiber (1070 nm) lasers are explored. Optimal parameters for sintering the Cu NPs are identified for each laser system, which targets low resistivity and high processing speed. Finally, the quality of the sintered tracks is quantified, and the laser sintering mechanisms observed under different wavelengths are analyzed. Practical considerations are discussed to improve the laser sintering process of Cu NPs.
关键词： laser sintering,printed electronics,copper nanoparticles
更新于2025-09-16 10:30:52
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A flexible non-enzymatic glucose sensor based on copper nanoparticles anchored on laser-induced graphene
摘要： An original flexible enzyme-free glucose amperometric biosensor based on Cu nanoparticles anchored on laser-induced graphene (Cu NPs-LIG) composite is successfully developed by a simple substrate-assisted electroless deposition (SAED) technique. The as-prepared Cu NPs-LIG sensor demonstrates an excellent glucose sensitivity of 495 μA mM-1 cm-2, ultrafast response time less than 0.5 s and the prominently low detection limit of 0.39 μM. Besides, the sensor shows extraordinary reproducibility, stability and selectivity in glucose sensing. Finally, a possible mechanism of the Cu NPs-LIG sensor for glucose sensing is proposed. Due to the simplicity preparation and performance reliability, the novel flexible Cu NPs-LIG sensor is an attractive candidate for next generation wearable and implantable non-enzymatic glucose diagnostic devices.
关键词： copper nanoparticles,non-enzymatic glucose sensor,electroless deposition,flexible,laser-induced graphene
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS) 2019 - Surakarta, Indonesia (20 July 2019)] INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS) 2019 - Effect of solvent in the synthesis of colloidal copper nanoparticles by pulse laser ablation method
摘要： Effect of solvent in the synthesis of colloidal copper nanoparticles by pulse laser ablation method
关键词： pulse laser ablation,solvent effect,colloidal copper nanoparticles
更新于2025-09-16 10:30:52