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Highly ordered Au-decorated Ag nanorod arrays as an ultrasensitive and reusable substrate for surface enhanced Raman scattering
摘要： For surface-enhanced Raman spectroscopy (SERS) substrates, complexity of the fabrication process, sensitivity and stability are factors that need to be considered. We report a simple and novel method for preparing an effective substrate that greatly enhances SERS signals. The SERS substrate is fabricated by selectively electroless deposition of Ag nanoparticles in the highly ordered porous anodized aluminum oxide (AAO) template and then etching it to form Ag nanorod bundles structure, so that the Raman enhancement occurs in the gap between the nanorods and the top of the nanorod bundle, which is verified by finite element analysis. A peculiarity of this method is that this is the first time to synthesize Ag nanorod arrays structure by using it. The results indicated that this prepared substrate has special micro-nano structure and when rhodamine 6 G is selected as the detection reagent, the detection limit is as low as 10?16 M with excellent recyclability. This outstanding array structure has a promising practical application in SERS field.
关键词： Reproducibility,Electroless deposition,Micro-nano structure,SERS,Ag nanorod arrays
更新于2025-09-23 15:21:21
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Controlled Electroless Deposition of Noble Metals on Silicon Substrates Using Self-Assembled Monolayers as Molecular Resists to Generate Nanopatterned Surfaces for Electronics and Plasmonics
摘要： Electroless deposition of noble metals on silicon has applications in a wide range of fields including electronic circuitry, metal plating industry, lithography, and other fabrication techniques. In addition, studies using self-assembled monolayers (SAM) as resists for electroless deposition for controlled deposition have significant potential for aiding advancement in the fields of nano electronics, sensing applications, and fundamental studies. Herein, we discuss the development of appropriate plating solutions for controlled deposition of metallic gold and silver on Si(111) surfaces in the presence of an organic silane monolayer acting as a resist film for directed metal deposition to produce metal-monolayer hybrid surfaces while investigating microscopic plating trends. For this, plating solutions were optimized to deposit metal on bare silicon surfaces while avoiding deposition on the SAM protected areas. Trends in the electroless deposition of gold and silver on a Si(111) surface as a function of concentration of metal ions, NH4F, citric acid, sodium citrate, polyvinylpyrrolidone (PVP) and deposition time have been monitored under ambient conditions. The resulting surfaces were characterized using atomic force microscopy (AFM) and the stability of plating solutions was investigated by UV-Vis spectroscopy. For both gold and silver, we observed an increase in metal deposition when the concentration of NH4F, citric acid, and deposition time increased. The addition of PVP and the pH of the solution were also shown to have a significant effect on the metal deposition. The octadecyltrichlorosilane (OTS) SAM films act as effective nanoscale resists when the NH4F concentration is reduced from typical plating conditions. In particular, NH4F concentrations from 0.02-0.50 M and metal ions concentrations from 0.001-0.020 M were found to allow deposition of metal nanostructures on a bare Si surface while preserving OTS protected areas.
关键词： self-assembled monolayers,AFM,silver,controlled metal deposition,gold,Electroless deposition
更新于2025-09-23 15:19:57
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Enhancement of the second harmonic signal of nonlinear crystals by self-assembled gold nanoparticles
摘要： In second harmonic generation (SHG), the energy of two incoming photons, e.g., from a femtosecond laser, can be combined in one outgoing photon of twice the energy, e.g., by means of a nonlinear crystal. The SHG efficiency, however, is limited. In this work, the harvested signal is maximized by composing a hybrid system consisting of a nonlinear crystal with a dense coverage of plasmonic nanostructures separated by narrow gaps. The method of self-assembled diblock-copolymer-based micellar lithography with subsequent electroless deposition is employed to cover the whole surface of a lithium niobate (LiNbO3) crystal. The interaction of plasmonic nanostructures with light leads to a strong electric near-field in the adjacent crystal. This near-field is harnessed to enhance the near-surface SHG signal from the nonlinear crystal. At the plasmon resonance of the gold nanoparticles, a pronounced enhancement of about 60-fold SHG is observed compared to the bare crystal within the confocal volume of a laser spot.
关键词： gold nanoparticles,nonlinear crystal,second harmonic generation,lithium niobate,plasmonic nanostructures,electroless deposition,self-assembled diblock-copolymer-based micellar lithography,LiNbO3,SHG
更新于2025-09-23 15:19:57
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Full Solution-Processed Fabrication of Conductive Hybrid Paper Electrodes for Organic Optoelectronics
摘要： There is growing interest in the development of “green” electronics fabricated from “natural” materials, which could lead to renewable, sustainable and potential inexpensive organic optoelectronics. In this paper, a novel, facile and full-solution processed approach has been successfully demonstrated to fabricate a highly flexible and conductive paper electrode by electroless deposition with the dopamine molecules as an adhesion layer on the newly hybrid paper. The novel paper substrate was prepared through simple hot-press with commercial paper and polypropylene (PP) film. And it has smooth surface and improved mechanical property. Importantly, it is flexible and highly resistant to water, which was important for solution process. The obtained highly conductive paper exhibited smooth and hydrophobic surface with high reflection. In addition, these conductive papers also showed excellent mechanical flexibility and stability, indicating the strong adhesion between metal and hybrid paper, which facilitates the roll-to-roll process of the device. As a possible application, this paper electrode can be effectively used as a mechanical support and electrode in organic light-emitting diode (OLED), showing the potential possibility in future electronics.
关键词： adhesion,dopamine,hybrid paper,electroless deposition,conductive
更新于2025-09-23 15:19:57
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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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A Cosmetically Adaptable Transparent Strain Sensor for Sensitively Delineating Patterns in Small Movements of Vital Human Organs
摘要： Monitoring live movements of human body parts is becoming increasingly important in the context of biomedical and human machine technologies. The development of wearable strain sensors with high sensitivity and fast response is critical to addressing this need. In this article, we describe the fabrication of a wearable strain sensor made of a Au micromesh partially embedded in polydimethylsiloxane (PDMS) substrate. The sensor exhibits a high optical transmittance of 85%. The effective strain range for stretching is 0.02 to 4.5% for a gauge factor of over 108. In situ scanning electron imaging and infrared thermal microscopy analysis have revealed that nanometric break junctions form throughout the wire network under strain; strain increases the number of such junctions, leading to a large change in the sheet resistance of the mesh. This aspect has been examined computationally with the findings that wire segments break successively with increasing strain and resistance increases linearly for lower values of strain and non-linearly at higher values of strain due to formation of current bottlenecks. The semi-embedded nature of these Au microwires allow the broken wires to retract to the original positions, thus closing the nanogaps and regaining the original low resistance state. High repeatability as well as cyclic stability. have been demonstrated in live examples involving human body activity, importantly while mounting the sensor in strategic remote locations away from the most active site where strains are highest.
关键词： mastication sensing,electroless deposition,polydimethylsiloxane,crackle lithography,strain sensor
更新于2025-09-10 09:29:36
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Evaluation of electroless Pt deposition and electron beam Pt evaporation on p-GaAs as a photocathode for hydrogen evolution
摘要： This study examines the changes in the photoelectrochemical (PEC) properties with Pt morphology after wet (electroless Pt deposition) and dry (e-beam Pt evaporation) deposition of Pt on p-GaAs. The Pt morphology and composition of the p-GaAs surface differed depending on the Pt deposition method, which in turn affected the optical and PEC properties of Pt on the GaAs electrode. Thus, the findings of this study can help in gaining a clearer understanding of the manner in which these changes affect the operation of a GaAs PEC water-splitting electrode.
关键词： Electrocatalyst,Electron beam evaporation,Gallium arsenide,Water splitting,Electroless deposition,Platinum
更新于2025-09-04 15:30:14