Water-Based Route to Synthesis of High-Quality UV-Blue Photoluminescing ZnSe/ZnS Core/Shell Quantum Dots and their Physicochemical Characterization

2016 ◽  
Vol 680 ◽  
pp. 553-557 ◽  
Author(s):  
Yong Ling Ding ◽  
Hua Dong Sun ◽  
Kang Ning Sun ◽  
Fu Tian Liu
Keyword(s):  
Ph Value ◽  
Aqueous Media ◽  
Physicochemical Characterization ◽  
Luminescent Properties ◽  
Core Shell ◽  
Reaction Flask ◽  
High Quality ◽  
Shell Nanostructures ◽  
Thiol Ligand ◽  
Znse Nanocrystals

Epitaxially overgrowing a semiconductor material with higher bandgap around the QDs has proven to be a crucial approach for improving the PL efficiency and stability of nanocrystals. In this paper, a ZnS shell was deposited around ZnSe nanocrystal cores via a noninjection approach in aqueous media. The deposition procedure conducted at 100°C in a reaction flask in the presence of the shell precursor compounds, together with the crude ZnSe nanocrystal cores and the thiol ligand glutathione. The influences of various experimental variables, including the reaction time, amount of thiourea, as well as pH value, on the growth rate and luminescent properties of the obtained core/shell nanocrystals have been systematically investigated. In comparison with the original ZnSe nanocrystals, the PL efficiency of the obtained ZnSe/ZnS core/shell nanostructures can be improved significantly with a QY up to 62.8%.

Template-Directed Electrodeposition of SnO2 Nanotubes and 1D Zn/SnO2 Core-Shell Nanostructures

2013 ◽  
Vol 745-746 ◽  
pp. 275-280 ◽  
Author(s):  
Min Lai ◽  
Yi Jian ◽  
Yan Ma ◽  
Gai Ge Zheng ◽  
Kun Zhong ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Room Temperature ◽  
Ph Value ◽  
Stannic Oxide ◽  
Core Shell ◽  
One Dimensional ◽  
Shell Nanostructures ◽  
Oxide Nanostructures ◽  
Metal Oxide Nanostructures ◽  
Polycarbonate Membranes

Template-directed electrosynthesis has been employed widely to prepare solids of defined dimension. It offers controllable routes to create nanostructures. In this study, one electrochemical method to fabricate one-dimensional metal oxide nanostructures was developed. The electrochemistry strategy was employed to manipulate the pH value within the pores of a template and the growth of continuous one-dimensional metal oxide nanostructures was controlled. The strategy was exemplified by the growth of tin oxide nanotubes. At room temperature, the reduction of nitrate within pores was employed to electrogenerate hydroxide ions and drive local precipitation of stannic oxide nanotubes. The nanotube walls displayed nearly uniform thickness along their entire length which were obtained within commercial track-etched polycarbonate membranes. One-dimensional Zn/SnO2 core-shell nanostructures were achieved by the further electrodeposition of Zn within SnO2 nanotubes.

scholarly journals Metal-Enhanced Fluorescence and FRET in Multilayer Core-Shell Nanoparticles

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Jérémie Asselin ◽  
Mathieu L. Viger ◽  
Denis Boudreau
Keyword(s):  
Aqueous Media ◽  
Physical Stability ◽  
Medical Diagnostics ◽  
Core Shell ◽  
Electromagnetic Spectrum ◽  
Shell Nanoparticles ◽  
Shell Nanostructures ◽  
Donor And Acceptor ◽  
Low Toxicity ◽  
Core Shell Nanoparticles

In recent years, various methods for the synthesis of fluorescent core-shell nanostructures were developed, optimized, and studied thoroughly in our research group. Metallic cores exhibiting plasmonic properties in the UV and visible regions of the electromagnetic spectrum were used to increase substantially the brightness and stability of organic fluorophores encapsulated in silica shells. Furthermore, the efficiency and range of Förster resonant energy transfer (FRET) between donor and acceptor molecules located in the vicinity of the metallic core was shown to be enhanced. Such multilayer nanoparticle architectures offer, in addition to the aforementioned advantages, excellent chemical and physical stability, solubility in aqueous media, low toxicity, and high detectability. In view of these enviable characteristics, a plethora of applications have been envisioned in biology, analytical chemistry, and medical diagnostics. In this paper, advances in the development of multilayer core-shell luminescent nanoparticle structures and selected applications to bioanalytical chemistry will be described.

ZnO/ZnS Core/Shell Nanostructures on Biologically Inspired Gold Wires for Uric Acid Sensing

2020 ◽  
Vol 18 (6) ◽  
pp. 510-513
Author(s):  
Trishna Moni Das ◽  
Hoque Shehenaz Shamim ◽  
Dipjyoti Kalita ◽  
Sankar Moni Borah ◽  
Sunandan Baruah
Keyword(s):  
Gold Nanoparticles ◽  
Uric Acid ◽  
Aspergillus Niger ◽  
Monosodium Glutamate ◽  
Aqueous Media ◽  
Core Shell ◽  
Chloroauric Acid ◽  
Au Nps ◽  
Shell Nanostructures ◽  
Gold Wires

In this work, microwires of gold nanoparticles (Au NPs) were grown using the fungus Aspergillus niger as a biological template. Au NPs were synthesized through the reduction of chloroauric acid using monosodium glutamate (MSG) in an aqueous media. The MSG here, served as a nutritional trigger behind the self-organization of Au NPs on Aspergillus niger apart from being the reducing as well as stabilizing agent. The fungal hyphae coated with gold nanoparticles were spread over the glass slide. The ZnO/ZnS core/shell nanostructures were deposited in a 2 mm gap of gold microwires’ spread. Uric acid sensing behavior of these ZnO/ZnS core/shell nanostructures were studied using the gold microwires as electrode.

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

Fabrication and luminescent properties of core-shell InGaN/GaN multiple quantum wells on GaN nanopillars

2012 ◽  
Vol 100 (26) ◽  
pp. 261103 ◽  
Author(s):  
J.-R. Chang ◽  
S.-P. Chang ◽  
Y.-J. Li ◽  
Y.-J. Cheng ◽  
K.-P. Sou ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Luminescent Properties ◽  
Multiple Quantum Wells ◽  
Core Shell ◽  
Multiple Quantum

scholarly journals Iron Based Core-Shell Structures as Versatile Materials: Magnetic Support and Solid Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Christian Zambrzycki ◽  
Runbang Shao ◽  
Archismita Misra ◽  
Carsten Streb ◽  
Ulrich Herr ◽  
...  
Keyword(s):  
Water Purification ◽  
Functional Materials ◽  
Core Material ◽  
Solid Catalyst ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Shell Nanostructures ◽  
Sio2 Shell ◽  
Iron Based

Core-shell materials are promising functional materials for fundamental research and industrial application, as their properties can be adapted for specific applications. In particular, particles featuring iron or iron oxide as core material are relevant since they combine magnetic and catalytic properties. The addition of an SiO2 shell around the core particles introduces additional design aspects, such as a pore structure and surface functionalization. Herein, we describe the synthesis and application of iron-based core-shell nanoparticles for two different fields of research that is heterogeneous catalysis and water purification. The iron-based core shell materials were characterized by transmission electron microscopy, as well as N2-physisorption, X-ray diffraction, and vibrating-sample magnetometer measurements in order to correlate their properties with the performance in the target applications. Investigations of these materials in CO2 hydrogenation and water purification show their versatility and applicability in different fields of research and application, after suitable individual functionalization of the core-shell precursor. For design and application of magnetically separable particles, the SiO2 shell is surface-functionalized with an ionic liquid in order to bind water pollutants selectively. The core requires no functionalization, as it provides suitable magnetic properties in the as-made state. For catalytic application in synthesis gas reactions, the SiO2-stabilized core nanoparticles are reductively functionalized to provide the catalytically active metallic iron sites. Therefore, Fe@SiO2 core-shell nanostructures are shown to provide platform materials for various fields of application, after a specific functionalization.

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