scholarly journals Photosynthesis of Silver Nanoparticle – Carbon Quantum Dots Nanocomposites

2019 ◽  
Vol 16 (2) ◽  
pp. 118-124
Author(s):  
Xuan-Dung Mai ◽  
Quang-Trung Le ◽  
Lan-Anh Nguyen Thi ◽  
Phuong Nguyen Thi ◽  
Phuong Le Thi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Silver Ions ◽  
Carbon Quantum Dots ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Transmission Electron ◽  
Ir And Raman Spectroscopies ◽  
Surface Enhanced Raman ◽  
Potential Applications ◽  
Enhanced Raman Scattering

Nanocomposites (NCs) of silver nanoparticles (Ag NPs) and carbon quantum dots (CQDs) have been received increasing attention for diverse applications including sensing, photocatalyst, surface enhanced Raman scattering detection and antibacterial. Herein, we report a unique photosynthesis of Ag NPs-CQD using CQDs as photo-reducing agent. Highly luminescent CQDs were prepared by a hydrothermal method using a mixture of citric acid (CA) and ethylenediamine (EDA) as starting precursors. X-ray diffraction pattern (XRD), transmission electron microscope (TEM), infrared (IR) and Raman spectroscopies confirmed the formation of NCs. We have demonstrated that the formation of Ag NPs accompanied with the degradation of surface fluorophores, which responded for the resolved absorption peak at ca. 346 nm and high luminescence of pristine CQDs. The NCs showed excellent antibacterial affinity to Escherichia coli. The results provide new understandings on the interactions between CQDs and silver ions as well as potential applications of Ag NP – CQD nanocomposites.

A NOVEL SYNTHESIS METHOD FOR SILVER NANOPARTICLES USING MOLTEN ε-CAPROLACTAM AS SOLVENT AND REDUCING AGENT

NANO ◽  
2014 ◽  
Vol 09 (08) ◽  
pp. 1450085
Author(s):  
PENG LI ◽  
HOUSHENG XIA ◽  
GUISHENG YANG
Keyword(s):  
Silver Nanoparticles ◽  
Synthesis Method ◽  
Reducing Agent ◽  
Synthesis Process ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Transmission Electron ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

A precipitation–reduction synthesis method for silver nanoparticles ( Ag NPs) was developed. Molten ε-caprolactam (CL) was used not only as solvent but also as reducing agent and stabilizer. At first, Ag 2 O NPs was prepared by precipitation reaction of silver nitrate ( AgNO 3) and sodium hydroxide ( NaOH ) using molten CL as solvent at 100°C. Then, Ag 2 O NPs was in situ reduced into Ag NPs by molten CL at 120°C. Techniques of X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to monitor the synthesis process. With the increase of reduction time, monodispersed Ag 2 O NPs (ca. 3.7 nm) were integrated and larger Ag NPs (10–90 nm) were formed. Fourier transform infrared (FT-IR) results showed that the surface of Ag NPs was capped with about 0.9 wt.% of CL molecules. Surface enhanced Raman scattering (SERS) effect of Ag NPs was investigated using Rhodamine 6G as a probe molecule.

One-step preparation and characterization of core-shell SiO2/Ag composite spheres by pulse plating

2017 ◽  
Vol 24 (3) ◽  
pp. 423-427 ◽  
Author(s):  
Li Xiong ◽  
Xiangping Huang ◽  
Ya Liu ◽  
Liqing Pan
Keyword(s):  
Structural Characteristics ◽  
Pulse Plating ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Transmission Electron ◽  
Surface Enhanced Raman ◽  
One Step ◽  
Enhanced Raman Scattering ◽  
20 Nm

AbstractA simple method of one-step pulse plating was used in the fabrication of core-shell SiO2/Ag composite spheres. Structural characteristics and morphologies of the prepared SiO2/Ag composite spheres are characterized by means of X-ray diffraction, scanning electron microscope, and transmission electron microscopy. The Ag shell is uniformly coated on the surface of SiO2 spheres with the thickness of about 20 nm. Photoluminescence (PL) spectrum has revealed that PL of the core-shell samples is much stronger than that of bare SiO2 spheres. Raman spectrometer measurements show that the SiO2/Ag composite spheres have excellent surface-enhanced Raman scattering performance. In addition, the current-voltage characteristic of SiO2/Ag composite spheres has improved at the same time.

scholarly journals Halloysite Nanotubes with Immobilized Plasmonic Nanoparticles for Biophotonic Applications

2021 ◽  
Vol 11 (10) ◽  
pp. 4565
Author(s):  
Anastasiia V. Kornilova ◽  
Sergey M. Novikov ◽  
Galiya A. Kuralbayeva ◽  
Subhra Jana ◽  
Ivan V. Lysenko ◽  
...  
Keyword(s):  
Electric Fields ◽  
Halloysite Nanotubes ◽  
Plasmonic Nanoparticles ◽  
Ag Nps ◽  
Optical Extinction ◽  
Transmission Electron ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Halloysite nanotubes (HNTs) with immobilized gold (Au) and silver (Ag) nanoparticles (NPs) belong to a class of nanocomposite materials whose physical properties and applications depend on the geometry of arrangements of the plasmonic nanoparticles on HNT’ surfaces. We explore HNTs:(Au, Ag)-NPs as potential nano-templates for surface-enhanced Raman scattering (SERS). The structure and plasmonic properties of nanocomposites based on HNTs and Au- and Ag-NPs are studied by means of the transmission electron microscopy and optical spectroscopy. The optical extinction spectra of aqueous suspensions of HNTs:(Au, Ag)-NPs and spatial distributions of the electric fields are simulated, and the simulation results demonstrate the corresponding localized plasmonic resonances and numerous “hot spots” of the electric field nearby those NPs. In vitro experiments reveal an enhancement of the protein SERS in fibroblast cells with added HNTs:Ag-NPs. The observed optical properties and SERS activity of the nanocomposites based on HNTs and plasmonic NPs are promising for their applications in biosensorics and biophotonics.

scholarly journals Surface Modified Chitosan with Cadmium Sulfide Quantum Dots as Luminescent Probe for Detection of Silver Ions

2021 ◽  
Vol 33 (5) ◽  
pp. 1025-1030
Author(s):  
Chella Santhosh ◽  
R.S. Ernest Ravindran
Keyword(s):  
Quantum Dots ◽  
Cadmium Sulfide ◽  
Silver Ions ◽  
Aqueous Solubility ◽  
X Ray Diffraction ◽  
Modified Chitosan ◽  
Transmission Electron ◽  
Cds Qds ◽  
Surface Modified ◽  
Chitosan Composite

In present work, the surface modified cadmium sulfide quantum dots (CdS QDs) was synthesized with chitosan for the detection of silver ions. Chitosan was employed as matrix medium to fabricate CdS QDs, resulting in the formation of novel QDs/chitosan composite. The CdS quantum dots surface coated with chitosan were analyzed using UV-vis spectrophotometer, X-ray diffraction and transmission electron microscope. The chitosan + CdS QDs exhibited high aqueous solubility with better steadiness. By using chitosan + CdS, the silver ions were not only detected but also reduced to nanosize due to the reducing property of chitosan. The mechanism of fluorescence quenching of chitosan + CdS by Ag+ was investigated using photoluminescence spectroscopy.

Surface Enhanced Raman Scattering (SERS) Effects of 4-Aminothiophenol on Au Nanoparticles with Different Shapes

2020 ◽  
Vol 20 (9) ◽  
pp. 5959-5963 ◽  
Author(s):  
Xiaochuan Xu ◽  
Xiaofang Liu ◽  
Min He ◽  
Bin Liu ◽  
Jianhui Yang
Keyword(s):  
Catalytic Activity ◽  
Raman Scattering ◽  
Au Nanoparticles ◽  
Surface Enhanced Raman Scattering ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Different Shapes

Au nanoparticles with different shapes (nanosphere, nanoplate and nanorod) have been synthesized and were characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction and UV-vis absorption spectroscopy. We investigated the catalytic activity of Au nanoparticles with different morphologies as surface-enhanced Raman scattering substrates for the conversion of p-aminothiophenol to p,p′-dimercaptoazobenzene. The experimental results indicated that the order of catalytic activity is nanorod> nanoplate> nanosphere under 633 and 785 nm excitation. The current research provides some reliable insights and important references for exploration new catalysts and their catalytic activities from the perspectives of different sizes, morphology and crystal composition of nanomaterials.

scholarly journals Variability and improvement of optical and antimicrobial performances for CQDs/mesoporous SiO2/Ag NPs composites via in situ synthesis

2021 ◽  
Vol 10 (1) ◽  
pp. 403-411
Author(s):  
Youliang Cheng ◽  
Mingjie Wang ◽  
Changqing Fang ◽  
Ying Wei ◽  
Jing Chen ◽  
...  
Keyword(s):  
Uv Light ◽  
Carbon Quantum Dots ◽  
Diffusion Method ◽  
Ag Nps ◽  
Uniform Size ◽  
High Antibacterial Activity ◽  
Fluorescent Materials ◽  
Potential Applications ◽  
Mesoporous Sio2

Abstract To change the optical properties and improve the antibacterial performances of carbon quantum dots (CQDs) and Ag NPs, mesoporous SiO2 spheres were combined with them to form the composites. In this paper, CQDs with a uniform size of about 3.74 nm were synthesized using glucose as carbon source. Then, CQDs/mesoporous SiO2/Ag NPs composites were obtained in situ under UV light irradiating by using mesoporous SiO2 and Ag NO3 as the carrier and silver resource, respectively. The diameter of CQDs/mesoporous SiO2/Ag NPs particles was in the range of 200–250 nm. With the increase in irradiating time, the red-shift in the UV-Vis spectrum for as-prepared CQDs/mesoporous SiO2/Ag NPs composites was found, and the adsorption peak was widened. In addition, the composites showed a high antibacterial activity against Staphylococcus aureus and Escherichia coli via disc diffusion method. These results indicated that inhibition circles for Ag NPs/mesoporous SiO2/CQDs and mesoporous SiO2/Ag NPs were similar in diameter. Furthermore, the two composites had a better bactericidal performance compared with other particles. Therefore, as-prepared CQDs/mesoporous SiO2/Ag NPs composites in this paper have great potential applications for fluorescent materials and antibacterial materials.

scholarly journals Size Control of Synthesized Silver Nanoparticles by Simultaneous Chemical Reduction and Laser Fragmentation in Origanum majorana Extract: Antibacterial Application

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2326
Author(s):  
Entesar Ali Ganash ◽  
Reem Mohammad Altuwirqi
Keyword(s):  
Silver Nanoparticles ◽  
Irradiation Time ◽  
Chemical Reduction ◽  
Size Control ◽  
Reduction Process ◽  
Laser Wavelength ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Transmission Electron ◽  
Origanum Majorana

In this work, silver nanoparticles (Ag NPs) were synthesized using a chemical reduction approach and a pulsed laser fragmentation in liquid (PLFL) technique, simultaneously. A laser wavelength of 532 nm was focused on the as produced Ag NPs, suspended in an Origanum majorana extract solution, with the aim of controlling their size. The effect of liquid medium concentration and irradiation time on the properties of the fabricated NPs was studied. While the X-ray diffraction (XRD) pattern confirmed the existence of Ag NPs, the UV–Vis spectrophotometry showed a significant absorption peak at about 420 nm, which is attributed to the characteristic surface plasmon resonance (SPR) peak of the obtained Ag NPs. By increasing the irradiation time and the Origanum majora extract concentration, the SPR peak shifted toward a shorter wavelength. This shift indicates a reduction in the NPs’ size. The effect of PLFL on size reduction was clearly revealed from the transmission electron microscopy images. The PLFL technique, depending on experimental parameters, reduced the size of the obtained Ag NPs to less than 10 nm. The mean zeta potential of the fabricated Ag NPs was found to be greater than −30 mV, signifying their stability. The Ag NPs were also found to effectively inhibit bacterial activity. The PLFL technique has proved to be a powerful method for controlling the size of NPs when it is simultaneously associated with a chemical reduction process.

scholarly journals Laser-Induced Deposition of Plasmonic Ag and Pt Nanoparticles, and Periodic Arrays

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 10
Author(s):  
Daria V. Mamonova ◽  
Anna A. Vasileva ◽  
Yuri V. Petrov ◽  
Denis V. Danilov ◽  
Ilya E. Kolesnikov ◽  
...  
Keyword(s):  
Substrate Surface ◽  
Pt Nanoparticles ◽  
Single Step ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
X Ray ◽  
Periodic Arrays ◽  
Potential Applications ◽  
Surface Decoration ◽  
Wide Potential

Surfaces functionalized with metal nanoparticles (NPs) are of great interest due to their wide potential applications in sensing, biomedicine, nanophotonics, etc. However, the precisely controllable decoration with plasmonic nanoparticles requires sophisticated techniques that are often multistep and complex. Here, we present a laser-induced deposition (LID) approach allowing for single-step surface decoration with NPs of controllable composition, morphology, and spatial distribution. The formation of Ag, Pt, and mixed Ag-Pt nanoparticles on a substrate surface was successfully demonstrated as a result of the LID process from commercially available precursors. The deposited nanoparticles were characterized with SEM, TEM, EDX, X-ray diffraction, and UV-VIS absorption spectroscopy, which confirmed the formation of crystalline nanoparticles of Pt (3–5 nm) and Ag (ca. 100 nm) with plasmonic properties. The advantageous features of the LID process allow us to demonstrate the spatially selective deposition of plasmonic NPs in a laser interference pattern, and thereby, the formation of periodic arrays of Ag NPs forming diffraction grating

Intense multi-state visible absorption and full-color luminescence of nitrogen-doped carbon quantum dots for blue-light-excitable solid-state-lighting

2016 ◽  
Vol 4 (38) ◽  
pp. 9027-9035 ◽  
Author(s):  
Daqin Chen ◽  
Weiwei Wu ◽  
Yongjun Yuan ◽  
Yang Zhou ◽  
Zhongyi Wan ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Solid State ◽  
Carbon Quantum Dots ◽  
Solid State Lighting ◽  
Visible Absorption ◽  
Nitrogen Doped ◽  
Full Color ◽  
Potential Applications ◽  
Doped Carbon Dots ◽  
Nitrogen Doped Carbon

Nitrogen-doped carbon dots with multi-state visible absorption and full-color blue/yellow/red emissions are synthesized, and show potential applications in solid-state-lighting.

The effect of silver concentration and calcination temperature on structural and optical properties of ZnO:Ag nanoparticles

2015 ◽  
Vol 29 (01) ◽  
pp. 1450254 ◽  
Author(s):  
M. Shayani Rad ◽  
A. Kompany ◽  
A. Khorsand Zak ◽  
M. E. Abrishami
Keyword(s):  
Calcination Temperature ◽  
Sol Gel ◽  
Visible Emission ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Zno Nps ◽  
Calcination Temperatures ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Average Size

Pure and silver added zinc oxide nanoparticles ( ZnO -NPs and ZnO : Ag -NPs) were synthesized through a modified sol–gel method. The prepared samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. In the XRD patterns, silver diffracted peaks were also observed for the samples synthesized at different calcination temperatures of 500°C, 700°C, 900°C except 1100°C, in addition to ZnO . TEM images indicated that the average size of ZnO : Ag -NPs increases with the amount of Ag concentration. The PL spectra of the samples revealed that the increase of Ag concentration results in the increase of the visible emission intensity, whereas by increasing the calcination temperature the intensity of visible emission of the samples decreases.

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