• Title, Summary, Keyword: Ag nanoparticles

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Radiolytic Synthesis of Ag-Loaded Polystyrene(Ag-PS) Nanoparticles and Their Antimicrobial Efficiency Against Staphylococcus aureus and Klebsiella pneumoniase

  • Oh, Seong-Dae;Byun, Bok-Soo;Lee, Seung-Ho;Choi, Seong-Ho;Kim, Moon-Il;Park, Hyun-Gyu
    • Macromolecular research
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    • v.15 no.4
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    • pp.285-290
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    • 2007
  • Ag nanoparticles were distributed onto polystyrene nanoparticle (PS-Ag) beads using two synthetic methodologies. In the first methodology, polystyrene (PS) beads were prepared via emulsion polymerization, with Ag nanoparticles subsequently loaded onto the surface of the PS beads. The polymerization of styrene was radiolytically induced in an ethanol (EtOH)/water medium, generating PS beads. Subsequently, Ag nanoparticles were loaded onto the PS beads via the reduction of Ag ions. The results from the morphological studies, using field emission transmission electron microscopy (FE-TEM), reveal the PS particles were spherical and nanosized, and the average size of the PS spherical particles decreased with increasing volume % of water in the polymerization medium. The size of the PS spherical particles increases with increasing radiation dose for the polymerization. Also, the amount of Ag nanoparticle loading could be increased by increasing the irradiation dose for the reduction of the Ag ions. In the second methodology, the polymerization of styrene and reduction of Ag ions were simultaneously performed by irradiating a solution containing styrene and Ag ions in an EtOH/water medium. Interestingly, the Ag nanoparticles were preferentially homogeneously distributed within the PS particles (not on the surface of the PS particles). Thus, Ag nanoparticles were distributed onto the surface of the PS particles using the first approach, but into the PS clusters of the particles via the second. The antimicrobial efficiency of a cloth coated with the Ag-PS composite nanoparticles was tested against bacteria, such as Staphylococcus aureus and Klebsiella pneumoniase, for 100 water washing cycles.

Influence of silver nanoparticles on the photovoltaic parameters of silicon solar cells

  • Dzhafarov, Tayyar D.;Pashaev, Arif M.;Tagiev, Bahadur G.;Aslanov, Shakir S.;Ragimov, Shirin H.;Aliev, Akper A.
    • Advances in nano research
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    • v.3 no.3
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    • pp.133-141
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    • 2015
  • Influence of Ag nanoparticles on optical and photovoltaic properties of, silicon substrates, silicon solar cells and glass have been investigated. Silver nanoparticles have been fabricated by evaporation of thin Ag layers followed by the thermal annealing. The surface plasmon resonance peak was observed in the absorbance spectrum at 470 nm of glass with deposited silver nanoparticles. It is demonstrated that deposition of silver nanoparticles on silicon substrates was accompanied with a significant decrease in reflectance at the wavelength 360-1100 nm and increase of the absorption at wavelengths close to the band gap for Si substrates. We studied influence of Ag nanoparticles on photovoltaic characteristics of silicon solar cells without and with common use antireflection coating (ARC). It is shown that silver nanoparticles deposited onto the front surface of the solar cells without ARC led to increase in the photocurrent density by 39% comparing to cells without Ag nanoparticles. Contrary to this, solar cells with Ag nanoparticles deposited on front surface with ARC discovered decrease in photocurrent density. The improved performance of investigated cells was attributed to Ag-plasmonic excitations that reduce the reflectance from the silicon surface and ultimately leads to the enhanced light absorption in the cell. This study showed possibility of application of Ag nanoparticles for the improvement of the conversion efficiency of waferbased silicon solar cells instead of usual ARC.

Synthesis of Ag/TiO2 Core/Shell Nanoparticles with Antibacterial Properties

  • Lin, Yue;Qiqiang, Wang;Xiaoming, Zhang;Zhouping, Wang;Wenshui, Xia;Yuming, Dong
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2607-2610
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    • 2011
  • Monodispersed Ag/$TiO_2$ core/shell nanoparticles were synthesized in solution via colloid-seeded deposition process using Ag nanoparticles as colloid seeds and $Ti(SO_4)_2$ as Ti-source respectively. Silver nitrate was reduced to Ag nanoparticles with $N_2H_4{\cdot}H_2O$ in the presence of CTAB as stabilizing agent. The titania sols hydrolyzed by the $Ti(SO_4)_2$ solution deposited on the surface of Ag nanoparticles to form the Ag/$TiO_2$ core/shell nanoparticles. Inductively coupled plasma atomic emission spectrometry (ICP-AES) showed low amount of Ag ion leaching from the Ag/$TiO_2$ core/shell nanoparticles. The Ag/$TiO_2$ core/shell nanoparticles indicated excellent antibacterial effects against Escherichia coli and maintained long-term antibacterial property.

Preparation and Stabilization of Ag Nanoparticles in 1-Amino-4-methylpiperazine

  • Park, Heon-Soo;Shin, Ueon-Sang;Kim, Hae-Won;Gong, Myoung-Seon
    • Bulletin of the Korean Chemical Society
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    • v.32 no.1
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    • pp.273-276
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    • 2011
  • Uniform Ag nanoparticles (< 10 nm) were effectively prepared in 1-amino-4-methylpiperazine as a solvent with multiple functions including reduction and stabilization. An Ag-complex such as $Ag_2(ehac)_2(eha)_2$ (ehac = 2-ethylhexylammonium carbamate; eha = 2-ethylhexylamine) was used as an Ag-precursor, whereas the usage of a salt such as $AgNO_3$ showed the formation of Ag nanoparticles in larger and irregular size (30 - 500 nm). The Ag nanoparticles (< 10 nm) prepared by using the Ag-complex could also be effectively stabilized by 1-amino-4-methylpiperazine. Transmission electron micrographs confirmed that the Ag particles were spherical and in the nanometer size.

Preparation of PEBAX-5513/Ag Nanoparticles/7,7,8,8-tetracyanoquinodimethane Composites for Olefin Separation and Analysis of Anions (올레핀 분리용 PEBAX-5513/Ag Nanoparticles/7,7,8,8-tetracyanoquinodimethane 복합체 제조 및 음이온 효과 분석)

  • Kim, Soyoung;Kang, Sang Wook
    • Membrane Journal
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    • v.29 no.5
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    • pp.246-251
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    • 2019
  • Facilitated transport membranes using silver nanoparticles as carriers for olefin/paraffin separation have been interested. $AgBF_4$ has been used as a precursor of silver nanoparticles in previous studies. However, relatively expensive $AgBF_4$ is not suitable for commercialization, and thus, PEBAX-5513/AgNPs (precursor: $AgClO_4$)/7,7,8,8-tetracyanoquinodimethane (TCNQ) composite membranes were prepared using silver nanopaticles with relatively inexpensive $AgClO_4$ precursors. Composite membranes of various compositions were prepared for PEBAX-5513/AgNPs/TCNQ composites, but no separation performance was observed. As a result of FT-IR analysis, it was confirmed that silver nanoparticles were formed in the PEBAX-5513 polymer and the surface of Ag nanoparticles was polarized by TCNQ, but the formed silver nanoparticles were not stabilized. From these results, it was concluded that the anion of the precursor plays an important role in the olefin/paraffin separation.

Enhanced Photo Current in n-ZnO/p-Si Diode Via Embedded Ag Nanoparticles for the Solar Cell Application

  • Ko, Young-Uk;Yun, Ho-Jin;Jeong, Kwang-Seok;Kim, Yu-Mi;Yang, Seung-Dong;Kim, Seong-Hyeon;Kim, Jin-Sup;An, Jin-Un;Eom, Ki-Yun;Lee, Hi-Deok;Lee, Ga-Won
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.15 no.1
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    • pp.35-40
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    • 2015
  • In this study, an n-ZnO/p-Si heterojunction diode with embedded Ag nanoparticles was fabricated to investigate the possible improvement of light trapping via the surface plasmon resonance effect for solar cell applications. The Ag nanoparticles were fabricated by the physical sputtering method. The acquired current-voltage curves and optical absorption spectra demonstrated that the application of Ag nanoparticles in the n-ZnO/p-Si interface increased the photo current, particularly in specific wavelength regions. The results indicate that the enhancement of the photo current was caused by the surface plasmon resonance effect generated by the Ag nanoparticles. In addition, minority carrier lifetime measurements showed that the recombination losses caused by the Ag nanoparticles were negligible. These results suggest that the embedding of Ag nanoparticles is a powerful method to improve the performance of n-ZnO/p-Si heterojunction solar cells.

PL and TL behaviors of Ag-doped SnO2 nanoparticles: effects of thermal annealing and Ag concentration

  • Zeferino, R. Sanchez;Pal, U.;Melendrez, R;Flores, M. Barboza
    • Advances in nano research
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    • v.1 no.4
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    • pp.193-202
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    • 2013
  • In this article, we present the effects of Ag doping and after-growth thermal annealing on the photoluminescence (PL) and thermoluminescence (TL) behaviors of $SnO_2$ nanoparticles. $SnO_2$ nanoparticles of 4-7 nm size range containing different Ag contents were synthesized by hydrothermal process. It has been observed that the after-growth thermal annealing process enhances the crystallite size and stabilizes the TL emissions of $SnO_2$ nanostructures. Incorporated Ag probably occupies the interstitial sites of the $SnO_2$ lattice, affecting drastically their emission behaviors on thermal annealing. Both the TL response and dose-linearity of the $SnO_2$ nanoparticles improve on 1.0% Ag doping, and subsequent thermal annealing. However, a higher Ag content causes the formation of Ag clusters, reducing both the TL and PL responses of the nanoparticles.

Light Scattering Effect of Incorporated PVP/Ag Nanoparticles on the Performance of Small-Molecule Organic Solar Cells

  • Heo, Il-Su;Park, Da-Som;Im, Sang-Gyu
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.221-221
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    • 2012
  • Small-molecule organic photovoltaic cells have recently attracted growing attention due to their potential for the low-cost fabrication of flexible and lightweight solar modules. The PVP/Ag nanoparticles were synthesized by the reaction of poly vinylpyrrolidone (PVP) and silver nitrate at $150^{\circ}C$. In the reaction, the size of the nanoparticles was controlled by relative mole fractions between PVP and Ag. The PVP/Ag nanoparticles with various sizes were then spin coated on the patterned ITO glass prior to the deposition of the PEDOT:PSS hole transport layer. The scattering of the incident light caused by these incorporated nanoparticles resulted in an increase in the path length of the light through the active layer and hence the enhancement of the light absorption. This scattering effect increased as the size of the nanoparticles increased, but it was offset by the decrease in total transmittance caused by the non-transparent nanoparticles. As a result, the maximum power conversion efficiency, 0.96% which was the value enhanced by 14% compared to the cell without incorporation of nanoparticles, was obtained when the mole fraction of PVP:Ag was 24:1 and the size of the nanoparticles was 20~40 nm.

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Rapid Synthesis of AgInS2/ZnS Core/Shell Nanoparticles and Their Luminescence Property

  • Lee, Seung Jae;Kim, Da Hea;Jung, Jongjin;Park, Joung Kyu
    • Rapid Communication in Photoscience
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    • v.4 no.2
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    • pp.45-47
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    • 2015
  • We have successfully synthesized $AgInS_2$ core and $AgInS_2$/ZnS core/shell nanoparticles by the sonochemical method. The ultrasonic based $AgInS_2$ and $AgInS_2$/ZnS nanoparticle synthesis can be utilized as a simple and rapid method. The $AgInS_2$/ZnS nanoparticles show the higher fluorescence intensity and quantum yield than $AgInS_2$ nanoparticles. Fluorescence wavelength of $AgInS_2$/ZnS shows blue shift from 635 nm to 610 nm against $AgInS_2$ because of reducing the defect sites and increasing spatial confinements. For the fluorescence lifetime, $AgInS_2$/ZnS (124.8 ns) has longer lifetime than $AgInS_2$ (54.8 ns).

Photocatalytic Properties of the Ag-Doped TiO2 Prepared by Sol-Gel Process/Photodeposition (졸-겔공정/광증착법을 이용한 Ag-Doped TiO2 합성 및 광촉매 특성)

  • Kim, Byeong-Min;Kim, Jung-Sik
    • Korean Journal of Materials Research
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    • v.26 no.2
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    • pp.73-78
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    • 2016
  • $TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.