scholarly journals Surfactant-dependant thermally induced nonlinear optical properties of l-ascorbic acid-stabilized colloidal GNPs and GNP–PVP thin films

RSC Advances ◽  
2019 ◽  
Vol 9 (27) ◽  
pp. 15502-15512 ◽  
Author(s):  
A. L. Sunatkari ◽  
S. S. Talwatkar ◽  
Y. S. Tamgadge ◽  
G. G. Muley

Gold nanoparticle (GNP) colloids stabilized with various concentrations of l-ascorbic acid were synthesized by the chemical reduction method and characterized by UV-Vis spectroscopy, XRD, FT-IR spectroscopy and TEM.

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ke Zhang ◽  
Rashid A. Ganeev ◽  
Konda Srinivasa Rao ◽  
Sandeep Kumar Maurya ◽  
Ganjaboy S. Boltaev ◽  
...  

The nonlinear optical properties of the aqueous solutions of silver nanoparticles (Ag NPs) prepared by chemical reduction method are analyzed using femtosecond and picosecond pulses at different wavelengths. In the case of 800 and 400 nm, the growths of nonlinear absorption and nonlinear refraction with the increase of Ag NP concentration, as well as a change at the signs of nonlinear optical processes, are determined. The nonlinear absorption coefficient and nonlinear refractive index of Ag NP solutions measured using picosecond pulses were a few orders of magnitude larger than those in the case of femtosecond probe pulses. We also demonstrate the optical limiting properties of Ag NPs using 800 nm, 60 fs pulses.


NANO ◽  
2013 ◽  
Vol 08 (03) ◽  
pp. 1350030 ◽  
Author(s):  
ERIC FRIBOURG-BLANC ◽  
DUNG THI MY DANG ◽  
TUYET THI THU LE ◽  
CHINH DUNG TRINH ◽  
THANH THI NU THANH ◽  
...  

This paper discusses the function of hydrogen peroxide and trisodium citrate (TSC) in the synthesis of silver ( Ag ) nanoplates through a simple chemical reduction method in ambient conditions. By this method, high purity Ag nanoplates were successfully generated (up to 100%). It was found that the amounts of hydrogen peroxide and TSC added to the solution are key to controlling the shape of Ag nanoparticles from spherical nanoparticles to hexagonal nanoplates and triangular nanoplates, depending on the Ag -to-hydrogen peroxide ratio and the Ag -to-TSC ratio used. This unique shape evolution process was carefully followed by a combination of ultraviolet-visible (UV-Vis) spectroscopy and transmission electron microscopy (TEM). The mean edge length of the triangular nanoplates varies from 65 nm to 100 nm. Polyvinyl pyrrolidone (PVP) is shown to increase the in-plane dimensions of the nanoplates as its relative concentration to Ag increases.


2007 ◽  
Vol 124-126 ◽  
pp. 1205-1208 ◽  
Author(s):  
Keun Ju Park ◽  
Dong Seok Seo ◽  
Woo Yang Jang ◽  
Jong Kook Lee

Nano-sized silver particles are considered to apply a silver paste for electrode because of its high conductivity on sintering at low temperature. In this study, silver nanoparticles as seeds were prepared by chemical reduction method with capping agent. Silver particles were prepared using SDS (Sodium dodecyl sulfate) as a surfactant and silver nanoparticles as seeds and reacted with ascorbic acid as a reduction agent. The silver seeds with 10-20 nm in size with uniform distribution were formed and the size and shape of silver particles were strongly dependent on the concentration of surfactant.


Author(s):  
Bang-on Nokkrut ◽  
Sawitree Pisuttipiched ◽  
Somwang Khantayanuwong ◽  
Buapan Puangsin

Metal nanoparticle has been reported to have a high antimicrobial activity against fungi, bacteria, and yeasts. In this study, silver nanoparticles (AgNPs) were synthesized using a chemical reduction method, at 90 oC, and used as an antifungal coating in paper packaging, to control the growth of C. gloeosporioides in cut orchid flowers during shipping. AgNPs were characterized by UV-Vis spectroscopy and atomic force microscope (AFM). The results indicated that the shape of AgNPs was spherical and homogenous with an average size of 47 nm. Twenty and 50 particles per million (ppm) concentration of AgNPs, mixed with starch, were prepared as the coating solution. The paper coated with 50 ppm AgNPs exhibited a significant antifungal activity against C. gloeosporioides compared to 20 ppm AgNPs coating. The AgNPs coated paper had a better water resistance and mechanical properties compared to paper without coating. We observed a significant reduction in the number of anthers, of orchid inflorescences, infected by C. gloeosporioides, when stored in the coated boxes. The current study demonstrates that paper boxes coated with AgNPs are a potential solution to control the infection of C. gloeosporioides in the storage of cut orchid flowers.


Coatings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 40
Author(s):  
Bang-on Nokkrut ◽  
Sawitree Pisuttipiched ◽  
Somwang Khantayanuwong ◽  
Buapan Puangsin

Metal nanoparticles have been reported to have a high antimicrobial activity against fungi, bacteria, and yeasts. In this study, we aimed to synthesize silver nanoparticles (AgNPs) using a chemical reduction method at 90 °C. The obtained AgNPs were used as an antifungal coating on packaging paper, to control the growth of Colletotrichum gloeosporioides in cut orchid flowers during the shipping process. The AgNPs were characterized by a UV-Vis spectroscopy and atomic force microscope (AFM). The results indicated that their shape was spherical and homogenous, with an average size of 47 nm. An AgNPs concentration of 20 and 50 particles per million (ppm), mixed with starch, was prepared as the coating solution. The paper coated with a concentration of 50 ppm exhibited a significant antifungal activity against C. gloeosporioides compared to 20 ppm. The coated paper had a higher water resistance and better mechanical properties compared to the uncoated paper. Additionally, we observed a significant reduction in the number of orchid inflorescence anthers, infected by C. gloeosporioides, when stored in the coated boxes. The current study demonstrates that paper boxes, coated with AgNPs, can be used in controlling the C. gloeosporioides infection during storage of cut orchid flowers.


Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1040
Author(s):  
Juan Garcés ◽  
Ramón Arrué ◽  
Néstor Novoa ◽  
Andreia F. Peixoto ◽  
Ricardo J. Chimentão

Copper nanoparticles (NPs) and ZrO2-supported copper NPs (Cu NPs/ZrO2) were synthesized via a chemical reduction method applying different pH (4, 7 and 9) and evaluated in a glycerol dehydration reaction. Copper NPs were characterized with transmission electron microscopy (TEM) and UV–vis spectroscopy. Transmission electron microcopy (TEM) results revealed a homogeneous distribution of copper NPs. A hypsochromic shift was identified with UV–vis spectroscopy as the pH of the synthesis increased from pH = 4 to pH = 9. Zirconia-supported copper NPs catalysts were characterized using N2 physisorption, X-ray diffraction (XRD), TEM, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), temperature-programmed desorption of ammonia (NH3-TPD) and N2O chemisorption. The presence of ZrO2 in the chemical reduction method confirmed the dispersion of the copper nanoparticles. X-ray diffraction indicated only the presence of tetragonal zirconia patterns in the catalysts. XPS identified the Cu/Zr surface atomic ratio of the catalysts. TPR patterns showed two main peaks for the Cu NPS/ZrO2 pH = 9 catalyst; the first peak between 125 and 180 °C (region I) was ascribed to more dispersed copper species, and the second one between 180 and 250 °C (region II) was assigned to bulk CuO. The catalysts prepared at pH = 4 and pH = 7 only revealed reduction at lower temperatures (region I). Copper dispersion was determined by N2O chemisorption. With NH3-TPD it was found that Cu NPs/ZrO2 pH = 9 exhibited the highest total quantity of acidic sites and the highest apparent kinetic constant, with a value of 0.004 min−1. The different pH applied to the synthesis media of the copper nanoparticles determined the resultant copper dispersion on the ZrO2 support, providing active domains for glycerol conversion.


2016 ◽  
Vol 34 (4) ◽  
pp. 806-810 ◽  
Author(s):  
Zhi Gang Wu ◽  
Yan Rong Jia ◽  
Jian Wang ◽  
Yang Guo ◽  
Jian Feng Gao

AbstractCore-shell SiO2/Ag composite spheres with dense, complete and nanoscaled silver shell were prepared by using a novel facile chemical reduction method without surface modification of silica at room temperature. The core-shell composites were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy and energy dispersive X-ray spectroscopy (EDX). The photocatalytic properties towards the degradation of methyl orange (Mo) of the prepared SiO2/Ag composites were also tested. The studies showed that the surface of SiO2 microspheres was homogeneously and completely covered by Ag nanoparticles and the composite exhibited excellent photocatalytic activities. The possible reaction mechanisms for the formation of the silica-silver core-shell spheres were also discussed in this paper.


2016 ◽  
Vol 863 ◽  
pp. 85-89 ◽  
Author(s):  
Y.S. Tamgadge ◽  
Gajanan G. Muley

This article reports investigations on thermally stimulated third order nonlinear absorption in Cu-PVP nanocomposite thin films. Cu nanoparticles have been obtained using chemical reduction method and thin films of Cu-PVP nanocomposites have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD), Ultraviolet-visible (UV-vis) spectroscopy, Fourier infra-red (FT-IR) spectroscopy, etc. for structural and linear optical studies. Third order nonlinear absorption studies have been performed using open aperture z-scan technique under continuous wave (CW) He-Ne laser. Cu-PVP nanocomposites are found to exhibit strong nonlinear absorption coefficient stimulated by thermal lensing effect.


2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Pham Van Viet ◽  
Hai Thi Nguyen ◽  
Thi Minh Cao ◽  
Le Van Hieu

We report on the process of synthesizing copper nanoparticles (Cu Nps) for a short reactive time by chemical reduction method with a support of CTAB reductive agent. Their properties were determined by ultraviolet-visible (UV-Vis) absorption spectrum, the X-ray (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), and Transmission Electron Microscopy (TEM) images. The antifungal activity of Cu Nps was evaluated by testing againstFusariumsp. The Cu Nps were obtained with the average size in the range of 20–50 nm having spherical shape. The survey shows that when Cu Nps were used at 450 ppm concentration in 9-day incubation, 93.98% of fungal growth was inhibited.


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