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TiO2 nanotube arrays modified with nanoparticles of platinum group metals (Pt, Pd, Ru): enhancement on photoelectrochemical performance
摘要： Highly ordered TiO2 nanotube arrays (TiO2 NTs) were synthesized by anodization method using a titanium foil and further modified with nanoparticles (? = 2~10 nm) of three platinum group metals (that is, platinum, palladium, and ruthenium) through potentiostatic pulsed electrodeposition method to obtain the composite material. Compared with pure TiO2 NTs, all the three composite samples (M-TiO2 NTs, M = Pt, Pd, Ru) showed different enhancement effects on the light responses, as well as different photoelectrochemical performances. In this study, the performance of M-TiO2 NTs, which worked as photoanode and cathode, was investigated. Ru-TiO2 exhibited the best degradation yield (~ 85.8%) when applied as photoanode under visible light illumination, which indicated the platinum group metal could also be induced under visible irradiation, not just served as the co-catalyst. M-TiO2 NTs as cathode were evaluated under the hydrogen evolution reaction (HER). The three M-TiO2 NT electrodes showed an improved efficiency over pure TiO2 NTs, while Pt-TiO2 NTs performed even better (without any sacrificial agent) with higher Faradic efficiency than platinum electrode in the photoelectrocatalytic hydrogen production, which could be explained by the uniform and fine metal nanoparticles on the surface of TiO2 NTs to offer abundant active sites for the reaction.
关键词： Platinum group metal nanoparticles,Photoelectrocatalysis,Water splitting,Hydrogen production,TiO2 nanotube arrays
更新于2025-09-19 17:15:36
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Hierarchical assembly of silver and gold nanoparticles in two-dimension: Toward fluorescence enhanced detection platforms
摘要： Two-dimensional (2D) metal nanoparticle platforms hold great potential in high-throughput point-of-care testing on basis of their excellent fluorescence enhancement effect. Self-assembly of metal nanoparticles (NPs) is versatile but simple for the preparation of 2D platforms; however, the surface charges on NPs would repel each other and induce large gaps on platforms, which hinder the generation of intense hotspots in electromagnetic fields and thus weaken the fluorescence enhancement effect. Here, we presented the hierarchical assembly of large-sized silver (Ag) NPs and small-sized gold (Au) NPs for constructing fluorescence enhanced platforms. The small Au NPs with weak fluorescence were chosen to complementarily fill into the larger gaps of the pre-assembled Ag platforms for increasing the electromagnetic hotspots. The resulting Ag/Au hybrid platforms (1-, 3- and 6-Ag/Au) exhibited growing fluorescence enhancement effects and the maximum enhanced factor reached 3.6-fold. The inserting of small Au NPs enhanced the fluorescence emission of fluorescent dye (cyanine-5) on the Ag platforms, especially on the monolayer 1-Ag platform, which increased by 161.6%. Moreover, the finite-difference time-domain (FDTD) calculations revealed the underlying cause of the improved electromagnetic fields in the Ag/Au hierarchical architecture in comparison to the Ag or Au NP. This work presents the hierarchical assembly is expected to be a powerful tool in the large-scale fabrication of fluorescence enhanced detection platforms.
关键词： Hotspot,Metal nanoparticles,Fluorescence enhancement,Self-assembly,Plasmon coupling
更新于2025-09-19 17:15:36
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Laser-Induced Optoacoustic Spectroscopy Studies of Inorganic Functionalized Metallic Nanorods
摘要： Plasmonic nanoparticles can be used in photothermal therapy thanks to their ability to generate local heat. The light-to-heat conversion efficiency is crucial for therapeutic and diagnostic applications. The photothermal properties of gold nanorods functionalized with silica layers of controllable thickness were characterized using both theoretical and experimental approaches. The time-resolved laser-induced optoacoustic spectroscopy (LIOAS) was used to determine the amount of absorbed energy changed promptly into heat. The heat generation efficiencies were simulated by the means of finite integration technique. The obtained parameters were correlated with silica thickness. Experimental results are consistent with theoretical predictions, thus LIOAS is a unique reliable method for studying photothermal effect in gold nanoparticles.
关键词： noble metal nanoparticles,finite integration technique,laser-induced optoacoustic spectroscopy,surface plasmon resonance,photothermal effect
更新于2025-09-19 17:13:59
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A highly flexible and selective dopamine sensor based on Pt-Au nanoparticle-modified laser-induced graphene
摘要： A highly flexible and selective electrochemical sensor based on a Pt-Au nanoparticles (Pt-AuNPs) modified laser-induced graphene (LIG)/Polydimethylsiloxane (PDMS) electrode is presented for the detection of dopamine (DA). The Pt-AuNPs exhibited high electrocatalytic activity in response to the oxidation of DA, and the peak current of DA detected by the Pt-AuNPs/LIG/PDMS electrode linearly increased with DA concentration. The fabricated sensor also exhibited an excellent sensitivity of approximately 865.80 μA/mM cm?2 and a detection limit of 75 nM in a neutral solution. In addition, it showed high selectivity for interfering compounds such as like uric acid (UA) and ascorbic acid (AA). Clearly defined current peaks, with a separation of approximately 0.11 V, were observed for DA and UA. Finally, DA was successfully detected in human urine.
关键词： Metal nanoparticles,Laser-induced graphene,Dopamine,Flexible substrate,Electrochemical sensor
更新于2025-09-19 17:13:59
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Self‐Assembly of Nanoparticle‐Spiked Pillar Arrays for Plasmonic Biosensing
摘要： Plasmonic biosensors have demonstrated superior performance in detecting various biomolecules with high sensitivity through simple assays. Scaled-up, reproducible chip production with a high density of hotspots in a large area has been technically challenging, limiting the commercialization and clinical translation of these biosensors. A new fabrication method for 3D plasmonic nanostructures with a high density, large volume of hotspots and therefore inherently improved detection capabilities is developed. Specifically, Au nanoparticle-spiked Au nanopillar arrays are prepared by utilizing enhanced surface diffusion of adsorbed Au atoms on a slippery Au nanopillar arrays through a simple vacuum process. This process enables the direct formation of a high density of spherical Au nanoparticles on the 1 nm-thick dielectric coated Au nanopillar arrays without high-temperature annealing, which results in multiple plasmonic coupling, and thereby large effective volume of hotspots in 3D spaces. The plasmonic nanostructures show signal enhancements over 8.3 × 108-fold for surface-enhanced Raman spectroscopy and over 2.7 × 102-fold for plasmon-enhanced fluorescence. The 3D plasmonic chip is used to detect avian influenza-associated antibodies at 100 times higher sensitivity compared with unstructured Au substrates for plasmon-enhanced fluorescence detection. Such a simple and scalable fabrication of highly sensitive 3D plasmonic nanostructures provides new opportunities to broaden plasmon-enhanced sensing applications.
关键词： surface diffusion,plasmonic biosensors,spherical metal nanoparticles,3D nanostructures,surface energy
更新于2025-09-19 17:13:59
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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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Laser-induced incandescence on metal nanoparticles: validity of the Rayleigh approximation
摘要： Time-resolved laser-induced incandescence (TiRe-LII) is increasingly being used to characterize non-carbonaceous nanoparticles. However, there exist several measured phenomena, particularly on metal nanoparticles, that cannot be explained using traditional models. This paper shows that some of these phenomena may be due to errors caused by the Rayleigh approximation of Mie theory, which is a standard approach for modeling the spectral absorption of carbonaceous nanoparticles but is generally invalid for metal nanoparticles. Other measurement phenomena can be explained by combining Mie theory with a polydisperse particle size distribution or by considering the change in the refractive index as the nanoparticles melt. Also, the effect of the nanoparticle charge on optical properties is investigated and is found to have a negligible effect on the TiRe-LII model.
关键词： Mie theory,Polydisperse particle size distribution,Metal nanoparticles,Refractive index,Nanoparticle charge,Rayleigh approximation,Laser-induced incandescence
更新于2025-09-19 17:13:59
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Light-trapping strategy for PEDOT:PSS/c-Si nanopyramid based hybrid solar cells embedded with metallic nanoparticles
摘要： In this article, we have investigated the combined role of nanopyramid (NP) array and metal nanoparticles (MNPs) in enhancing the light trapping ability and improving the photo-absorption of PEDOT:PSS/c-Si Hybrid Solar Cells (HSCs) using a 3D ?nite-di?erence time-domain (FDTD) method. A parametric optimization of the essential geometrical parameters of NPs and MNP is performed based on short circuit current density (Jsc). The optimization result reveals that maximum Jsc of 35.91 mA/cm2 is achievable with top textured NP (without MNPs) which is 24.38% higher than the planar counterpart. However, the absorption spectrum is broadened with the insertion of Al MNP at rear side of the HSC. This is also accompanied by almost two fold increase in Jsc to 41.71 mA/cm2 which is 44.47% higher the planar HSCs. The photovoltaic parameters such as Jsc, Voc, PCE and Fill Factor (FF) are calculated using the DEVICE software for NP and NP embedded with Al MNPs based c-Si Solar Cells. The physics at the interface of inorganic nanostructure and organic material layer is thoroughly described. In addition to this, we have tried to decode the underlying physics for the enhancement of photon absorption in nanopyramidal structures and MNPs structures through an extensive analysis of the photo- generation rate, electric ?eld intensity, power absorption pro?les, PCE and FF of nanopyramidal, nanopyramidal with MNP and planar HSCs.
关键词： Absorption,Metal nanoparticles,Short circuit current density,Nanopyramid,PEDOT:PSS,FDTD,Hybrid solar cells
更新于2025-09-19 17:13:59
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Numerical Investigation of Ultrashort Laser-Ablative Synthesis of Metal Nanoparticles in Liquids Using the Atomistic-Continuum Model
摘要： We present a framework based on the atomistic continuum model, combining the Molecular Dynamics (MD) and Two Temperature Model (TTM) approaches, to characterize the growth of metal nanoparticles (NPs) under ultrashort laser ablation from a solid target in water ambient. The model is capable of addressing the kinetics of fast non-equilibrium laser-induced phase transition processes at atomic resolution, while in continuum it accounts for the effect of free carriers, playing a determinant role during short laser pulse interaction processes with metals. The results of our simulations clarify possible mechanisms, which can be responsible for the observed experimental data, including the presence of two populations of NPs, having a small (5–15 nm) and larger (tens of nm) mean size. The formed NPs are of importance for a variety of applications in energy, catalysis and healthcare.
关键词： metal nanoparticles,femtosecond laser ablation,dual nanoparticle distribution,pulsed laser ablation in liquids
更新于2025-09-16 10:30:52
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The amorphization of metal nanoparticles in graphitic shells under laser pulses
摘要： It is shown that graphitic shells encapsulating metal nanoparticles facilitate the amorphization of metals and stabilize the amorphous phase against recrystallization. In an in-situ electron microscopy experiment, where the objects are exposed to laser pulses during their observation, the amorphization of iron and cobalt nanocrystals in graphitic shells is demonstrated. The infrared nanosecond pulses lead to fast melting of the metal which then dissolves carbon atoms from the shell. Fast cooling of the liquid solution after the pulse results in the solidification of an amorphous metal-carbon phase. The amorphous phase is metastable and can be recrystallized by repeated laser pulses or slow thermal annealing. The recrystallization needs heterogeneous nucleation but is unfavorable at the metal-graphite interface and so stabilizes the amorphous phase against recrystallization. The analysis of the experiments explains the formation mechanisms of an amorphous metal-carbon phase as a metastable solution of carbon in a transition metal and shows how that the encapsulation by a graphitic shell can be a route towards the stabilization of otherwise unfavorable amorphous metal or metal-carbon phases.
关键词： amorphization,electron microscopy,metal nanoparticles,graphitic shells,laser pulses
更新于2025-09-16 10:30:52