The self-assembly synthesis of tungsten oxide quantum dots with enhanced optical properties

2015 ◽  
Vol 3 (14) ◽  
pp. 3280-3285 ◽  
Author(s):  
Songling Wang ◽  
Stephen V. Kershaw ◽  
Guisheng Li ◽  
Michael K. H. Leung
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Tungsten Oxide ◽  
Self Assembly ◽  
The Self ◽  
One Pot ◽  
Photoluminescence Emission ◽  
Microwave Assisted ◽  
Blue Photoluminescence

A one-pot microwave-assisted methodology was explored to fabricate ultrafine WO3 quantum dots, with excellent thermal/photonic stabilities favorable for blue photoluminescence emission and photochromic performance.

scholarly journals One-pot synthesis of graphene quantum dots and simultaneous nanostructured self-assembly via a novel microwave-assisted method: impact on triazine removal and efficiency monitoring

RSC Advances ◽  
2018 ◽  
Vol 8 (52) ◽  
pp. 29939-29946 ◽  
Author(s):  
Beatriz Fresco-Cala ◽  
M. Laura Soriano ◽  
Alice Sciortino ◽  
Marco Cannas ◽  
Fabrizio Messina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Self Assembly ◽  
Graphene Quantum Dots ◽  
One Pot ◽  
Graphene Quantum Dot ◽  
Microwave Assisted ◽  
Microwave Reaction ◽  
One Step ◽  
Microwave Assisted Method

Graphene quantum dot (GQDs) assemblies from a one-step microwave reaction as bifunctional materials in remediation of triazines.

scholarly journals Nucleation of Ga droplets self-assembly on GaAs(111)A substrates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Artur Tuktamyshev ◽  
Alexey Fedorov ◽  
Sergio Bietti ◽  
Stefano Vichi ◽  
Riccardo Tambone ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Size Distribution ◽  
Self Assembly ◽  
Cluster Size ◽  
Droplet Size Distribution ◽  
Local Environment ◽  
The Self ◽  
Critical Cluster ◽  
Droplet Nucleation ◽  
High Degree

AbstractWe investigated the nucleation of Ga droplets on singular GaAs(111)A substrates in the view of their use as the seeds for the self-assembled droplet epitaxial quantum dots. A small critical cluster size of 1–2 atoms characterizes the droplet nucleation. Low values of the Hopkins-Skellam index (as low as 0.35) demonstrate a high degree of a spatial order of the droplet ensemble. Around $$350\,^{\circ }\hbox {C}$$ 350 ∘ C the droplet size distribution becomes bimodal. We attribute this observation to the interplay between the local environment and the limitation to the adatom surface diffusion introduced by the Ehrlich–Schwöbel barrier at the terrace edges.

Size-Controlled Microwave-Assisted Synthesis of Water-Dispersible Cd(Se,S) Quantum Dots for Potential Biological Applications

2015 ◽  
Vol 1784 ◽  
Author(s):  
E. Calderón-Ortiz ◽  
S. Bailón-Ruiz ◽  
L. Alamo-Nole ◽  
J. Rodriguez-Orengo ◽  
O. Perales-Perez
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Quantum Confinement Effect ◽  
Reactive Oxygen Species Generation ◽  
Size Control ◽  
Average Crystallite Size ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted

ABSTRACTNanomedicine is fostering significant advances in the development of platforms for early detection and treatment of diseases. Nanoparticles (NPs) like quantum dots (QDs) exhibit size-dependent optical properties for light-driven technologies, which might become important in bio-imaging, sensing and photo-dynamic therapy (PDT) applications. The present research addresses the synthesis of water-stable Cd-based QDs via a Microwave-Assisted synthesis approach using cadmium sulfate salt, and thioglycolic acid as Cd- and S-precursors, respectively. Selenide ions were available by reductive leaching of metallic Selenium in Sodium bisulfite solution. The size control and the tunability of the optical properties were achieved by a suitable control of the reaction temperature (in the 140°C- 190°C range) and reaction time (10 minutes-40 minutes). X-ray diffraction analyses suggested the development of a CdSe,S face cubic centered structure; the broadening of the diffraction peaks indicated the presence of very small nanocrystals in the samples. The average crystallite size was estimated at 5.50 nm ± 1.17nm and 3.72 nm ± 0.04 nm, for nanoparticles synthesized at 180°C after 40 minutes or 10 minutes of reaction, respectively. HRTEM images confirmed the crystalline nature and the small size of the synthesized nanocrystals. In turn, the exciton was red-shifted from 461nm to 549 nm when the reaction temperature was prolonged from 140°C to 190 °C, suggesting the crystal growth. The corresponding band gap values were approximately 2.2 eV, confirming the quantum confinement effect (bulk value 1.74eV). This red shift was also evidenced in PL measurements where the main emission peak was shifted from 507 nm to 564 nm when the samples were excited at 420 nm. A narrow size-tunable emission also was supported by the full width at half maximum (∼ 45 nm) for the synthesized nanocrystals. The reactive oxygen species generation capability of as-synthesized QDs was also investigated. The correlation between the particle size and the generation of (ROS) by the degradation of methylene blue was evident with a reduction of MB concentration from 10μM to 7.5μM and 6.7μM after 15 minutes of UV irradiation for reaction time of 10 min. and 40 min. respectively. No additional degradation was noticed after 60 minutes of irradiation.

Multivariate optimization of optical properties of CdSe quantum dots obtained by a facile one-pot aqueous synthesis

2019 ◽  
Vol 6 (6) ◽  
pp. 1350-1360 ◽  
Author(s):  
Isabelle Moraes Amorim Viegas ◽  
Beate Saegesser Santos ◽  
Adriana Fontes ◽  
Giovannia Araujo de Lima Pereira ◽  
Claudete Fernandes Pereira
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Cdse Quantum Dots ◽  
Multivariate Optimization ◽  
High Quality ◽  
One Pot ◽  
Aqueous Synthesis ◽  
Synthesis Procedure

Four parameters are simultaneously optimized to provide a simple, fast and reproducible synthesis procedure to obtain high-quality CdSe quantum dots.

Nanoparticles as template for porphyrin nanostructure growth

2019 ◽  
Vol 23 (04n05) ◽  
pp. 526-533 ◽  
Author(s):  
Mariana Hamer ◽  
Rolando M. Caraballo ◽  
Peter J. Eaton ◽  
Craig Medforth
Keyword(s):  
Self Assembly ◽  
Soret Band ◽  
Surface Interactions ◽  
Water Soluble ◽  
The Self ◽  
Stacking Interactions ◽  
Aromatic System ◽  
One Pot ◽  
Assembly Mechanism ◽  
Scattering Measurements

Porphyrins and metalloporphyrins are one of the most widely studied platforms for the construction of supramolecular structures. These compounds have an extended aromatic system that allows [Formula: see text]–[Formula: see text] stacking interactions which, together with hydrogen bonds, electrostatic forces and the formation of inter-metallic complexes arising from peripheral groups, offer a versatile platform to control the self-assembly mechanism. In this work, we present the study of nanostructures formed by self-assembly of the water-soluble porphyrins meso-tetra([Formula: see text]-methyl-4-pyridyl)porphyrin (TMPyP) and meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) in the presence of hard nanotemplates. Different nanoparticles (silica, gold, and polystyrene), concentrations and synthetic procedures were explored. The obtained materials were characterized by SEM and AFM microscopies, UV-vis absorption spectroscopy and dynamic light scattering measurements. A clear modification of the SiO2 NP surface roughness using one-pot synthesis was observed. The results were variable depending on the porphyrin–surface interactions and concentrations used. At lower porphyrin concentrations, a shift of the Soret band was observed, while at higher concentrations, free NS were formed. This reflects a competition between surface and solution directed self-assembly.

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