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Surfactant templated oriented 1-D nanoscale platinum and palladium systems on a modified silicon surface
摘要： A templating method has been improved to form oriented one-dimensional metal nanostructures on a silicon surface. To achieve this, the silicon surface is modified with 3-aminopropyl trimethoxysilane. The cationic surfactant cetyltrimethylammonium bromide is used as a micellar template. The average width of the obtained Pt strips is 35 nm, the average width of the obtained Pd strips is 60 nm.
关键词： Platinum group,Atomic force microscopy,Surface modification,Nanostructured materials,Micelle templates
更新于2025-09-23 15:23:52
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Controlled growth of Cu <sub/>2a??x</sub> S sheet-like nanoshells and Cu <sub/>2a??x</sub> Sa??CdS pa??n junctions on Au nanorods with coupled plasmon resonances and enhanced photocatalytic activities
摘要： In this study, we propose an approach to grow Cu2?xS sheet-like nanoshells on Au nanorods with the aid of Ag2S auxiliary templates. The Ag2S semi-shells are first grown on the side-surface of the Au nanorods and then, the Cu2?xS sheet-like nanoshells are selectively grown on the opposite side, which is beneficial for improving the controllability of the growth sites of the Cu2?xS sheet-like nanoshells. The Cu2?xS–CdS p–n junctions grown on Au nanorods are produced by replacing Ag+ with Cd2+ in the as-prepared Au/(Cu2?xS–Ag2S), so that Au/(Cu2?xS–CdS) heterorods with non-central symmetric shells of Cu2?xS–CdS p–n junctions are formed. By carefully adjusting the effective thickness of the Cu2?xS–CdS junctions, the optimized photocatalytic activity of the Au/(Cu2?xS–CdS) heterorods is obtained, and it is about 1.62 and 1.22-fold that of Au/Cu2?xS and Au/CdS, respectively. The improved photocatalytic performance of the Au/(Cu2?xS–CdS) heterorods is attributed to the effective charge carriers at the interfaces of CdS–Au, Cu2?xS–Au and the Cu2?xS–CdS p–n junction. Our findings provide a strategy for the optimal design of plasmon–exciton heterostructures with improved photocatalytic activity.
关键词： Cu2?xS,Ag2S auxiliary templates,plasmon resonances,photocatalytic activities,Au nanorods
更新于2025-09-19 17:13:59
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Fabrication of gold nanorod arrays on a cylindrical surface of optical fibers by using in-situ electrodeposition
摘要： Optical fiber is an excellent light-coupled substrate, which has the characteristics of large a length-diameter ratio with a cylindrical surface. Recently, various methods have been reported in order to improve the ability of local optical fields. In particular, methods aimed to address the efficient coupling and optical resonances by modifying metal nanostructures on the light-coupled substrate have been developed. However, existing methods are largely applicable to planar or tip substrates, and it remains a significant challenge to prepare metal nanostructures on a cylindrical substrate. In this study, we proposed a novel strategy to fabricate gold nanorods arrays (AuNRs) by electrodepositing them in anodized aluminum oxide (AAO) templates on the cylindrical surface of optical fibers. Briefly, AAO templates were prepared in-situ by using a constant current density secondary oxidation method on the cylindrical surface of optical fibers, and then the AuNRs were in-situ deposited in the AAO templates by electrodeposition. The features of the AuNRs such as diameter, nanorod pitch, and height could be easily regulated by adjusting the parameters of electrodeposition and the anode oxidation. The SEM images demonstrates that AuNRs exhibit a satisfactory consistency with a uniform diameter and favorable self-supporting properties. The relationships between the current density, pore diameter and pore distribution were explored, combined with the voltage-time curve during anodic oxidation. Furthermore, the surface plasmon resonance (SPR) optical properties of the AuNRs on the cylindrical surface were analyzed using the Finite-difference Time-domain Algorithm (FDTD) method. Results suggest that this alternative in-situ electrodeposition strategy has the potentials to be applied to SPR optical fiber sensing.
关键词： Gold nanorods arrays,Finite-difference time-domain algorithm,In-situ electrodeposition,Cylindrical surface of optical fibers,Anodized aluminum oxide templates
更新于2025-09-19 17:13:59
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Robust synthesis of Au‐based multishell structures as plasmonic catalysts for selective hydrogenation of 4‐nitrostyrene
摘要： In this paper, we describe a robust self-template strategy for facile and large-scale synthesis of porous multishell Au with controllable shell number, sphere size and in-situ surface modification. The process involved the rapid reduction of novel Au-melamine colloidal templates with a great amount of NaBH4 in presence of poly(sodium-p-styrenesulfonate) (PSS). After soaking the templates in other metal salt solution, the obtained bimetallic templates could also be generally converted into bimetallic multishell structures by same reduction process. In the hydrogenation of 4-nitrostyrene using NH3BH3 as a reducing agent, the porous triple-shell Au with surface modification (S-PTSAu) exhibited excellent selectivity (97 %) for 4-aminostyrene in contrast with unmodified triple-shell Au. Furthermore, it also showed higher enhancement of catalytic activity under irradiation of visible light as compared to similar catalysts with less shell number. This work opens up a new route in designing and synthesizing Au-based multishell structures for various applications.
关键词： Selectivity,Plasmonic catalysis,Self-sacrificial templates,Multishell Au,Hydrogenation
更新于2025-09-19 17:13:59
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Robust synthesis of Au-based multishell structures as plasmonic catalysts for selective hydrogenation of 4-nitrostyrene
摘要： In this paper, we describe a robust self-template strategy for facile and large-scale synthesis of porous multishell Au with controllable shell number, sphere size and in-situ surface modification. The process involved the rapid reduction of novel Au-melamine colloidal templates with a great amount of NaBH4 in presence of poly(sodium-p-styrenesulfonate) (PSS). After soaking the templates in other metal salt solution, the obtained bimetallic templates could also be generally converted into bimetallic multishell structures by same reduction process. In the hydrogenation of 4-nitrostyrene using NH3BH3 as a reducing agent, the porous triple-shell Au with surface modification (S-PTSAu) exhibited excellent selectivity (97 %) for 4-aminostyrene in contrast with unmodified triple-shell Au. Furthermore, it also showed higher enhancement of catalytic activity under irradiation of visible light as compared to similar catalysts with less shell number. This work opens up a new route in designing and synthesizing Au-based multishell structures for various applications.
关键词： Selectivity,Plasmonic catalysis,Self-sacrificial templates,Multishell Au,Hydrogenation
更新于2025-09-19 17:13:59
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Metallic Nanomaterials (Part B) || 5. Size-controlled atomically precise copper nanoclusters: Synthetic protocols, spectroscopic properties and applications
摘要： Noble metal nanoclusters (NCs) are a new class of nanomaterials which are considered being a missing link between isolated metal atoms and metal nanoparticles (NPs). The sizes of the NCs are comparable to the Fermi wavelength of the conduction electrons, and this renders them to be luminescent in nature. They exhibit size-dependent fluorescence properties spanning almost the entire breath of the visible spectrum. Among all the noble metal NCs being explored, copper NCs (CuNCs) are the most rarely investigated primarily because of their propensity of getting oxidised. In this chapter, we have given a comprehensive understanding as to why these NCs are luminescent in nature. We have also given a detailed overview regarding the various templates used for the synthesis of these CuNCs along with the respective protocols being followed. The various instrumental techniques used to characterize these CuNCs are discussed which provides an in-depth understanding as to how these CuNCs can be properly examined. Finally, we have highlighted some of the most recent applications of these CuNCs which make them unique to serve as the next-generation fluorophores.
关键词： nano-thermometry,bio-imaging,sensing,synthetic protocols,instrumentations,spectroscopic properties,templates,luminescent nanoclusters
更新于2025-09-16 10:30:52
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Mask-less MOVPE of arrayed n-GaN nanowires on site- and polarity-controlled AlN/Si templates
摘要： We present a novel approach to attain Ga-polar n-GaN nanowires on n-Si(111)/AlN templates, by site- and polarity-controlled metal organic vapor phase epitaxy. A three-stage process is developed to (i) form equally-sized Ga-polar GaN islands, (ii) change the growth direction towards the vertical direction and finally, to (iii) obtain continuous nanowire epitaxy. Homogeneous islands are achieved by minimizing parasitic nucleation and adjusting the adatom diffusion length to the used nanoimprint pattern. The influence of the carrier gas composition on the polarity is studied, achieving pure Ga-polarity by mostly using nitrogen carrier gas. Enhancing the Si/Ga-ratio leads to an amplification of the vertical growth, but also to a reduced number of NWs. 100% growth is attained by a height dependent V/III-ratio adjustment. The results are supported by a qualitative model, explaining how suppression of multi-pod, parasitic and inhomogeneous crystallization can be realized by trading off in situ SiNx passivation and localized GaN growth.
关键词： GaN nanowires,MOVPE,site-controlled,Si templates,polarity-controlled
更新于2025-09-12 10:27:22
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Layer-by-layer adsorption: Factors affecting the choice of substrates and polymers
摘要： The electrostatic layer-by-layer technique for fabrication of multi-layered structures of various sizes and shapes using flat and colloidal templates coupled with polyelectrolyte layer-forming materials has attracted significant interest among both academic and industrial researchers due to its versatility and relative simplicity of the procedures involved in its execution. Fabrication of the multi-layered structures using the electrostatic layer-by-layer method involves several distinct stages each of which holds great importance when considering the production of a high-quality product. These stages include selection of materials (both template and a pair of construction polyelectrolytes), adsorption of the first polyelectrolyte layer onto the selected templates, formation of the second layer comprised of the oppositely charged polyelectrolyte and guided by the interactions between the two chosen polyelectrolytes, and multi-layering, where a selected number of layers are produced, and which is conditioned by both intrinsic properties of the involved construction materials and external fabrication conditions such as temperature, pH and ionic strength. The current review summarises the most important aspects of each stage mentioned above and gives examples of the materials suitable for utilization of the technique and describes the underlying physics involved.
关键词： polyelectrolytes,electrostatic layer-by-layer,multi-layered structures,colloidal templates,fabrication conditions
更新于2025-09-10 09:29:36
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Synthesis, structures and applications as fluorescence probes of novel Hg(II)/Ag(I) functional supramolecular compounds based on nitrogen heterocyclic cations
摘要： Two new supramolecular polymers based on HgI2, AgI and BPMB·2Br{BLMB = 1, 4-bis [(4-picoline)-N-methylene] benzene} have been synthesized via the self-assembly reaction in solution. They were {(BPMB)[HgI4(H2O)0.66]}(1), and {(BPMB)2[Ag4I8]}(2).We analyzed the structures of compounds 1–2 by X-ray single-crystal diffraction, infrared spectroscopy (IR) and characterized the properties of compounds 1–2 by ?uorescence spectrum and ultraviolet-visible (UV-vis) absorption spectrum. The results indicated that compound 1 is the mononuclear structure; Compound 2 has the multinuclear cubane structure. Compounds 1–2 showed good photocatalytic abilities for methylene blue (MB) irradiated by visible light. The effective detection of Fe3+ was performed by compounds 1–2 as ?uorescent sensors.
关键词： Cationic templates,photocatalytic,supramolecularpolymer
更新于2025-09-09 09:28:46
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[IEEE 2018 26th European Signal Processing Conference (EUSIPCO) - Roma, Italy (2018.9.3-2018.9.7)] 2018 26th European Signal Processing Conference (EUSIPCO) - Privacy-Preserving Indexing of Iris-Codes with Cancelable Bloom Filter-based Search Structures
摘要： Protecting the privacy of the enrolled subjects is an important requirement expected from biometric systems. In recent years, numerous template protection schemes have been proposed, but so far none of them have been shown to be suitable for indexing (workload reduction) in the computationally expensive identification mode. This paper presents a, best to the authors’ knowledge, first method in the scientific literature for indexing protected iris templates. It is based on applying random permutations to Iris-Code rows, and subsequent indexing using Bloom filters and binary search trees. In a security evaluation, the unlinkability, irreversibility and renewability of the method are demonstrated quantitatively. The biometric performance and workload reduction are assessed in an open-set identification scenario on the IITD and CASIA-Iris-Thousand datasets. The method exhibits high biometric performance and reduces the required computational workload to less than 5% of the baseline Iris-Code system.
关键词： renewability,biometric systems,template protection,binary search trees,unlinkability,irreversibility,iris templates,Bloom filters
更新于2025-09-04 15:30:14