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Au@Cu Core-Shell Nanocubes with Controllable Sizes in the Range of 20-30 nm for Applications in Catalysis and Plasmonics
摘要： Predominantly covered by a single type of {100} facets, Cu nanocubes are attractive catalytic material toward reactions such as electrochemical reduction of CO2. Here we report a seed-mediated approach to the facile synthesis of Au@Cu core-shell nanocubes with hexadecylamine and Cl- serving as capping agents toward the {100} facets of Cu and glucose as a reducing agent. The large (12%) lattice mismatch between Cu and Au led to the localized epitaxial growth of Cu shells on the Au seeds and the formation of nanocubes with randomly distributed Au cores. Compared to the same synthesis in the absence of Au seeds, the reduction of Cu(II) ions was greatly accelerated in the presence of Au seeds because of the autocatalytic surface reduction. It was also found that the structure and morphology of the products were highly dependent on the concentration of Cu(II) precursor in the reaction solution. Nanoplates rather than nanocubes were obtained when the concentration of Cu(II) precursor was reduced down to a certain level. By varying the reaction time and/or the amount of Au seeds, the size of the Au@Cu nanocubes could be tuned in a range of 20–30 nm. The as-synthesized core-shell nanocubes exhibited a strong localized surface plasmon resonance peak at 581 nm and the resonance was dominated by absorption rather than scattering. It is expected that the Au@Cu nanocubes with uniform and controllable sizes will find use in a variety of applications such as plasmonics and catalysis.
关键词： lattice mismatch,Copper nanocubes,core-shell nanocrystals,plasmonics,seed-mediated growth
更新于2025-11-19 16:56:35
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Construction of Long Narrow Gaps in Ag Nanoplates
摘要： Hexagonal Ag nanoplates with long and ultra-narrow gaps (about 90 nm in length, 2 nm in width) are synthesized via seed-mediated growth method. By growing around the polymer shell on the seed, the Ag domain cannot merge at the meet-up point, leaving a long narrow gap in the resulting plate. These gapped nanoplates exhibit high sensitivity in SERS detection, with limitation of 10-9 M for 2-naphthalenethiol.
关键词： SERS,ultra-narrow gaps,Ag nanoplates,seed-mediated growth
更新于2025-09-23 15:21:01
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Gold Nanoearbuds: Seed-Mediated Synthesis and the Emergence of Three Plasmonic Peaks
摘要： We demonstrate the first successful synthesis of reasonably monodisperse and single crystalline gold nano-earbuds (Au NEBs) using a binary surfactant mixture of cetyltrimethylammonium chloride (CTAC) and benzyldimethylhexadecylammonium chloride (BDAC) in a seed-mediated growth method. We have focused on the key chemical parameters behind the formation and growth of Au NEBs to result in tunable dimensions (lengths 37-77 nm; widths 4-6 nm and aspect ratios 7-19), as a consequence of which the longitudinal surface plasmon resonance (LSPR) peak could be tuned beyond 1200 nm. The achievement of LSPR beyond 1200 nm while maintaining the dimension well below 100 nm is a challenging accomplishment in the realm of 1D Au nanostructures. This earbud-like morphology additionally exhibits three plasmonic peaks, rather uncommon for 1D nanostructure, which were analyzed theoretically based on finite element method. The new resonance peak of Au NEB was assigned as an additional longitudinal mode intensified by the bulbous ends as well as the high-aspect ratio, thereby providing conclusive evidence that it is indeed a new morphology.
关键词： Au nano-earbud,Seed-mediated growth,Surface plasmon resonance,1D nanostructure,3D finite element method
更新于2025-09-19 17:13:59
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Shell Thickness-Dependent Au@Ag Nanoparticles Aggregates for High-Performance SERS Applications
摘要： Plasmonic core-shell nanomaterials have attracted great attention and offered wide applications in surface-enhanced Raman spectroscopy (SERS) due to their unique localized surface plasmon resonance (LSPR) characteristics. In this study, the SERS performance of Ag coated Au nanoparticles aggregates (Au@AgNAs) substrate was explored. The fabrication of Au@AgNAs involved using spherical Au nanocrystals of 32 nm in diameter as the seeds, and ascorbic acid was used as the reductant. The thickness of the Ag shell deposited onto the Au surface was finely tuned from 3 to 13 nm by changing the amount of AgNO3 precursor. Results in this study suggested that the LSPR of the Au core was rapidly attenuated with increasing Ag shell thickness, while the LSPR bands for Ag shell blue-shifted from 390 to 420 nm. Au@AgNAs with the Ag shell thickness of 8.5 nm exhibited excellent SERS activity, which could realize detecting R6G at an ultralow concentration of 1×10?12 M. Besides, the prepared Au@AgNAs showed well homogeneity and reproducibility, and the limit of detection of thiram was calculated as 1.09×10?9 M, indicating that the Au@AgNAs substrate could be potentially used for high-performance SERS sensing applications.
关键词： SERS,core-shell nanoparticles,pesticide,seed-mediated growth,surface plasmonic property
更新于2025-09-09 09:28:46
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Sequential Growth of High Quality Sub-10 nm Core-Shell Nanocrystals: Understanding the Nucleation and Growth Process Using Dynamic Light Scattering
摘要： Monodisperse sub-10 nm core-shell nanocrystals have been extensively studied owing to their important applications in catalysis, bioimaging, nanomedicine and so on. In this work, an amorphous shell component-crystallization strategy has been proposed to prepare high quality sub-10 nm NaYF4:Yb/Er@NaGdF4 core-shell nanocrystals successfully via a sequential growth process. Dynamic light scattering technique has been used to investigate the secondary nucleation and growth process of forming the core-shell nanocrystals. The size and morphologies evolution of the core-shell nanocrystals reveal that the secondary nucleation of the shell component is unavoidable after hot-injecting of the shell precursor at high temperature, which followed by dissolution and re-crystallization process (an Ostwald Ripening process) to partially produce the core-shell nanocrystals. The present study demonstrates that the size of seed nanocrystals and the injection temperature of the shell component precursor play a vital role in formation of core-shell nanostructures completely. This work will provide an alternative strategy for precisely controllable fabrication of sub-10nm core-shell nanostructures for various applications.
关键词： Seed-mediated growth,Monodisperse,Core-shell nanoparticles,Dynamic light scattering
更新于2025-09-04 15:30:14