Photoinduced formation of colloidal Au by a near-infrared femtosecond laser

2003 ◽  
Vol 18 (7) ◽  
pp. 1710-1714 ◽  
Author(s):  
Chongjun Zhao ◽  
Shiliang Qu ◽  
Jianrong Qiu ◽  
Congshan Zhu
Keyword(s):  
Femtosecond Laser ◽  
Absorption Spectra ◽  
Near Infrared ◽  
Au Nanoparticles ◽  
X Ray Diffraction ◽  
Local Formation ◽  
X Ray ◽  
Transmission Electron ◽  
Red Color ◽  
Yellow Orange

A Au colloid was prepared in a 5 mM HAuCl4 solution through irradiation with a focused infrared femtosecond laser at 800 nm. The Au colloid was characterized by absorption spectra, transmission electron microscopy, and x-ray diffraction analysis. The appearance of absorption peak around 526 nm in the absorption spectra and the wine-red color of sample solution HAuCl4 under focused laser irradiation verified the formation of Au colloid. The solution color changed in the order of yellow → orange → wine-red due to the local formation of Au nanoparticles near the focus. The pulse energy, focus position of laser beam, and solvent composite play important roles in formation, grain size, and stability of the Au colloid. A mechanism for the precipitate of Au nanoparticles was proposed, and a multiphoton process of femtosecond laser was involved.

Effect of Au on the Performance of Porous Silicon/V2O5 Nanorods Heterojunctions to NO2 Gas

NANO ◽  
2016 ◽  
Vol 11 (07) ◽  
pp. 1650079 ◽  
Author(s):  
Wenjun Yan ◽  
Ming Hu ◽  
Jiran Liang ◽  
Dengfeng Wang ◽  
Yulong Wei ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Porous Silicon ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Analytical Techniques ◽  
Heating Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

A novel composite of Au-functionalized porous silicon (PS)/V2O5 nanorods (PS/V2O5:Au) was prepared to detect NO2 gas. PS/V2O5 nanorods were synthesized by a heating process of pure vanadium film on PS, and then the obtained PS/V2O5 nanorods were functionalized with dispersed Au nanoparticles. Various analytical techniques, such as field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), have been employed to investigate the properties of PS/V2O5:Au. Herein, the PS/V2O5:Au sample exhibited improved NO2-sensing performances in response, stability and selectivity at room temperature (25[Formula: see text]C), compared with the pure PS/V2O5 nanorods. These phenomena were closely related to not only the dispersed Au nanoparticles acting as a catalyst but also the p-n heterojunctions between PS and V2O5 nanorods. Whereas, more Au nanoparticles suppressed the improvement of response to NO2 gas.

Biosynthesis of silver nanoparticles using lavender leaf and their applications for catalytic, sensing, and antioxidant activities

2016 ◽  
Vol 5 (6) ◽  
Author(s):  
Brajesh Kumar ◽  
Kumari Smita ◽  
Luis Cumbal
Keyword(s):  
Silver Nanoparticles ◽  
Leaf Extract ◽  
Antioxidant Activities ◽  
Present Report ◽  
X Ray Diffraction ◽  
Visible Spectroscopy ◽  
X Ray ◽  
Transmission Electron ◽  
Red Color ◽  
Uv Visible

AbstractThe present report summarizes an eco-friendly approach for the biosynthesis of silver nanoparticles (AgNPs) using the leaf extract of lavender. Initially, the synthesis of AgNPs was visually observed by the appearance of a wine red color. The optical property, morphology, and structure of as-synthesized AgNPs were characterized by UV-visible spectroscopy, dynamic light scattering, transmission electron microscopy, and X-ray diffraction analyses. All characterization data revealed the formation of crystalline and spherical AgNPs (Ag/Ag

scholarly journals Synthesis of Dandelion-like Porous Au Nanoparticles for Catalytic Reduction of Nitrophenol

2020 ◽  
Vol 01 ◽  
Author(s):  
Huiying Wu ◽  
Feng Liang
Keyword(s):  
Active Sites ◽  
Au Nanoparticles ◽  
Catalytic Reduction ◽  
Molar Ratio ◽  
Void Space ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
Templating Method ◽  
X Ray ◽  
Transmission Electron

Background: Porous Au nanomaterials show great potential in the fields of biomedicine, drug delivery and catalysis for the merits of low density, large void space and large specific surface area. The preparation of porous Au nanomaterials is usually carried out by using a hard-templating method which is cumbersome. Methods: Dandelion-like porous Au nanoparticles were synthesized through a soft-templating method in our work. The synthesized porous Au nanoparticles were characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) and cyclic voltammetry (CV). The reduction of nitrophenol was carried out to evaluate the catalytic behavior of porous Au nanoparticles. Results: Porous Au nanoparticles prepared were in uniform size (47.9±6.4 nm) and the morphology could be regulated by adjusting the molar ratio of reactants. The apparent rate constant (kapp) value of reducing nitrophenol catalyzed by porous Au nanoparticles was higher than Au nanospheres and nanobranches in similar size. It could be attributed to the large amount of active sites and high proportion of high-order crystal faces proved by CV and XRD. Conclusion: We developed a facile and reproducible method for synthesizing porous Au nanoparticles. The morphology of porous Au nanoparticles can be ajusted by changing the molar ratio of reactants. Porous Au nanoparticles we prepared behaved better in catalysis compared with Au nanospheres and Au nanobranches.

Plasmon Enhanced Emission of Perovskite Quantum Dot Films

MRS Advances ◽  
2018 ◽  
Vol 3 (14) ◽  
pp. 733-739 ◽  
Author(s):  
Seyma Dadı ◽  
Yemliha Altıntas ◽  
Emre Beskazak ◽  
Evren Mutlugun
Keyword(s):  
Quantum Dot ◽  
Au Nanoparticles ◽  
Au Nanoparticle ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Transmission Electron ◽  
Coating Method ◽  
Photoluminescence Enhancement ◽  
Time Resolved Photoluminescence

ABSTRACTWe propose and demonstrate the photoluminescence enhancement of CsPbBr3 perovskite quantum dot films in the presence of Au nanoparticles. Embedded into a polymer matrix, Au nanoparticle- quantum dot film assemble prepared by an easy spin coating method enabled the photoluminescence enhancement of perovskite quantum dot films up to 78%. The properties of the synthesized perovskite QDs and gold nanoparticles have been analysed using high resolution transmission electron microscopy, X-ray diffraction, energy dispersive X- ray spectroscopy, UV-Vis absorption spectrophotometer, steady state and time-resolved photoluminescence spectrometer.

Preparation of TiO2/Ga2O3 Nanowires by a Sol-Gel-Solvothermal Method

2010 ◽  
Vol 663-665 ◽  
pp. 965-968
Author(s):  
Yue Hui Wang ◽  
Dong Jun Wang ◽  
Ai Jun Song ◽  
Zhi Gang Zhang ◽  
Shi Tao Song
Keyword(s):  
Electron Microscopy ◽  
Near Infrared ◽  
Solvothermal Method ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Tetrabutyl Titanate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
First Time

TiO2/Ga2O3 nanowires were successfully prepared by a sol–gel-solvothermal method using tetrabutyl titanate as precursor, alcohol as solvent, Ga2O3 as templet and dopants, alginate as dispersant. The structures, morphologies,compositions and catalytic activity of products have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy ( FESEM ), nitrogen adsorption test, ultraviolet-visible near-infrared spectroscopy (UV–vis–NIR ),energy dispersive X-ray (EDX) analysis and spectrophotometer. The results revealed that the as-synthesized TiO2/Ga2O3 nanowires grew along [001] direction,which is reported for the first time, and the as-prepared product had better optical activity than TiO2 nanoparticles. Finally, the nanowires have a good adsorption capacity of 128.2 m2/g tested through nitrogen adsorption.

scholarly journals Au/TiO2 catalysts prepared by borohydride reduction for preferential CO oxidation at near-ambient temperature

2019 ◽  
Vol 6 (1) ◽  
pp. 6-12 ◽  
Author(s):  
Georgia Barbalho Leal ◽  
Daniela C. Loureiro da Silva ◽  
Beatriz Naomy Watacabe ◽  
Ligia Ciotti ◽  
Rodolfo M. Antoniassi ◽  
...  
Keyword(s):  
Sodium Citrate ◽  
Au Nanoparticles ◽  
Borohydride Reduction ◽  
X Ray Diffraction ◽  
Excellent Performance ◽  
Preferential Co Oxidation ◽  
X Ray ◽  
Synthesis Parameters ◽  
Transmission Electron ◽  
Oxidation Of Carbon Monoxide

Abstract Au nanoparticles were prepared in solution using HAuCl4.3H2O as Au precursor, sodium citrate as stabilizing agent and sodium borohydride as reducing agent. The influence of synthesis parameters such as BH4:Au and Citrate:Au ratios were studied. In a further step, the stabilized Au nanoparticles were supported on TiO2 with different Au loadings (wt%). The resulting Au/TiO2 catalysts were characterized by Energy-dispersive X-ray spectroscopy, X-ray diffraction and Transmission Electron Microscopy and tested for the preferential oxidation of carbon monoxide in hydrogen-rich stream. Au nanoparticles stabilized in solution were obtained with sizes in the range of 3-4 nm. After supported on TiO2, the Au nanoparticles size did not change and the Au/TiO2 catalysts exhibited excellent performance and stability in the temperature range of 20 - 50°C.

scholarly journals Structure and Optical Property of Gold Nanoparticles Synthesized by Modified Polyol Method

2021 ◽  
Vol 31 (3) ◽  
Author(s):  
Long Nguyen Viet
Keyword(s):  
Gold Nanoparticles ◽  
Au Nanoparticles ◽  
Average Particle Size ◽  
Nir Spectroscopy ◽  
Polyol Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Modified Polyol Method

In this research, Au nanoparticles were successfully synthesized by modified polyol method with commercial precursors to be gold (III) chloride trihydrate (HAuCl4·3H2O), ethylene glycol (EG), poly(vinylpyrrolidone) (PVP), sodium borohydride (NaBH4). The structure and properties of as-prepared Au nanoparticles have been investigated by X ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis-NIR spectroscopy. As a result, Au nanoparticles with the average particle size of 28.80 nm were successfully synthesized in the range of about 50 nm. It is evidenced that the assembly of gold nanoparticles was presented in their nucleation, growth, and formation. 

Microscopical Study of Au Nanocrystals Self-Assembled on (100)Si and SiO2/(100)Si Substrates

2006 ◽  
Vol 959 ◽  
Author(s):  
Emanuela Piscopiello ◽  
Leander Tapfer ◽  
Marco Vittori Antisari ◽  
Pasquale Paiano ◽  
Paola Prete ◽  
...  
Keyword(s):  
Self Assembly ◽  
Au Nanoparticles ◽  
Microscopical Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Si Substrates ◽  
Au Film ◽  
Assembly Method ◽  
Transmission Electron

ABSTRACTThis work reports on the structural characterization of Au nanocrystals directly prepared on the surface of (100)Si and 150 nm-thick SiO2 deposited (100)Si substrates, by a physical self-assembly method, consisting in the UHV evaporation of a thin Au film and its successive high temperature annealing. The morphology, orientation, and crystalline structure of Au nanocrystals were characterized by scanning and high-resolution transmission electron microscopy and X-ray diffraction, respectively. Experimental results show that the nature of the substrate strongly influences the process of Au nanocrystal formation upon heat treatment, by affecting the interaction of deposited Au with the underlying material. In the case of clean (100)Si substrates the Au strongly interacts with Si, so that Au nanoislands are obtained with a well defined epitaxial relationships with the substrate, i.e. [100]AuÐÐ[110]Si and [110]AuÐÐ[311]Si. The nanoisland shape is affected by faceting at the Au/Si interface, the Au nanocrystal being limited by the {111}, {311}, {711} and {-111} planes of Si. In the case of SiO2/(100)Si substrates spherical shaped Au nanoparticles with random crystal orientation are instead, produced.

scholarly journals Synthesis of High-Yield Gold Nanoplates: Fast Growth Assistant with Binary Surfactants

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Changshun Wang ◽  
Caixia Kan ◽  
Jiejun Zhu ◽  
Xiaoling Zeng ◽  
Xiangfu Wang ◽  
...  
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Near Infrared ◽  
Infrared Region ◽  
Thermal Reduction ◽  
High Yield ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Simple Chemical ◽  
Strong Surface

A novel and simple chemical method was developed to fastly synthesize Au nanoplates with size of micrometers and tens of nanometers in thickness. The synthesis was carried out within 30 minutes by thermal reduction of precursors (HAuCl4) in the presence of binary surfactants Poly(vinylpyrrolidone) (PVP) and cetyltrimethylammonium bromide (CTAB) in ethylene glycol (EG) solution. The presence and concentration of PVP and CTAB in the growth solution play important roles in the fast formation of Au nanoplates. The obtained Au nanoplates exhibit strong surface plasmon absorption in the near-infrared region (NIR), displaying a considerable dependence on the shape and size. Characterizations by Transmission electron microscope and X-ray diffraction indicated that the nanoplates are single crystals with (111) planes as two basal surfaces. Explanations for the nuclei formation and crystal growth behind anisotropic Au nanoplates were proposed.

Strong Photoluminescence in the Near-Infrared from Colloidally-Prepared HgTe Nanocrystals

1998 ◽  
Vol 536 ◽  
Author(s):  
M. T. Harrison ◽  
S. V. Kershaw ◽  
M. G. Burt ◽  
A. L. Rogach ◽  
A. Kornowski ◽  
...  
Keyword(s):  
Room Temperature ◽  
Near Infrared ◽  
Nanocrystalline Material ◽  
X Ray Diffraction ◽  
Promising Candidate ◽  
X Ray ◽  
Infrared Luminescence ◽  
Telecommunication Systems ◽  
Transmission Electron ◽  
Dramatic Shift

AbstractWe report here the first measurement of strong near-infrared room temperature photoluminescence (PL) from colloidally-prepared HgTe nanocrystals. X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) measurements indicate that the nanoparticles are in the cubic coloradoite phase, with a diameter of approximately 4 nm. The absorption spectrum shows a pronounced electronic transition in the near-infrared, and the broad PL appears to consist of several overlapping features between 800 and 1400 nm with a peak at 1080 nm, which represent a dramatic shift from bulk HgTe behaviour. The quantum efficiency (QE) of the freshly prepared sample is around 50%, which is among the highest ever reported for a nanocrystalline material. Over a period of several days, the luminescence shifts further into the infrared yielding more dominant longer wavelength features. The observation of this strong infrared luminescence makes this material a promising candidate for application in optical telecommunication systems.

Sign in / Sign up

Export Citation Format

Share Document