Nanometer-sized Silver Particles Research Articles

Electrodeposition of Carbon from CO2 in Room-Temperature Ionic Liquid Triethylpentylphosphonium Bis(trifluoromethanesulfonyl)imide

The conversion of CO2 to solid carbon by the electrochemical method is an attractive process as a CO2 recycling technology, but the electrolyte has been limited to high-temperature molten salts. In this study, the electrodeposition of solid carbon from CO2 on an Ag substrate in triethylpentylphosphonium bis(trifluoromethanesulfonyl)imide at room temperature and 1 atm CO2 atmosphere was investigated. Cyclic voltammetry with multiple cycles revealed that the three potential steps causing reduction, oxidation, and reduction current are important for the carbon electrodeposition from CO2. Based on the cyclic voltammogram, potentiostatic electrolysis was performed in the three potential steps. Consequently, the Ag substrate was covered with a black film because of the electrodeposited solid carbon. Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy revealed that the deposits were composed of the electrodeposited solid carbon and nanometer-size silver particles coming from the Ag substrate. From the experimental results, we propose a model of the electrochemical formation mechanism of solid carbon from CO2 on the Ag substrate. This study shows that the electrochemical method has the potential to convert CO2 into valuable carbonaceous materials with optimized electrochemical parameters, even at room temperature, and that this technique will contribute to developing a carbon-circulation society.

Magnetic levitation force performance of benzil added bulk MgTi0,06B2 superconductors

MgB2 superconductors can be proposed as a good candidate for Maglev systems due to their superior structural and superconducting properties. Besides, magnetic levitation and guidance force properties of these superconductors should be increased for commercial applications of Maglev systems. Therefore, the critical current density and magnetic levitation and guidance force properties of MgTi0.06B2 superconducting samples were investigated in this study, at measurement temperatures of 20 K and 25 K, depending on benzil (C14H10O2) addition in different adding amounts of 0, 1.5, 3, 4.5, 6 and 9 wt%. In addition to benzil, nanometer-sized silver particles were added to the samples in a constant ratio of 2 wt% to enhance the structural properties. The maximum critical current density values increased from 67 kA/cm2 for pure sample to 92 kA/cm2 with benzil adding amount of 3 wt% at T = 20 K, indicating an increment of 37%. In addition, the levitation force in ZFC (zero field cooling) regime and the guidance force in FC (field cooling) regime at 20 K increased at an amount of 46% and 57%, respectively, with 3% benzil addition. It can be said that the suitable amount of benzil addition as a carbon source produces additional pinning centres inside the MgTi0.06B2 and thus structural properties, critical current density and therefore, magnetic levitation properties of the samples are increased.

Antibacterial ability of immobilized silver nanoparticles in agar-agar films co-doped with magnesium ions

The antibacterial ability of in situ prepared nanometer-sized silver particles, immobilized in agar-agar films, was studied as a function of the concentration of co-dopant, magnesium ions. Content of inorganic components in hybrid films was determined using inductively coupled plasma optic emission spectroscopy, and found to be low (<2 wt.-%). Morphology of prepared hybrid films, studied by transmission electron microscopy, revealed the presence of non-agglomerated and randomly distributed 10–20 nm silver nanoparticles (Ag NPs) within the agar-agar matrices. Fourier-transform infrared spectroscopy indicated the distinct chemical interaction between Ag NPs and polymer chains. Thermogravimetric analysis, as well as the determination of tensile strength, Young’s modulus, and elongation at break showed improvement of thermal stability and mechanical properties of agar-agar matrices upon the incorporation of Ag NPs due to high compatibility between the hydrophilic organic component and inorganic components. The complete microbial reduction of Gram-positive bacteria Staphylococcus aureuswas observed for all agar-silver films, while satisfactory results were observed for Gram-negative bacteria Pseudomonas aeruginosa (≥99.6%). The release of Ag+ ions is suppressed by the increase of the concentration of Mg2+ ions and it was found to be significantly smaller (≤0.24 ppm) than the harmful ecological level (1 ppm).

Nonlinear polarization in metal nanocomposite system based photonic crystals

The properties of third-order nonlinear susceptibility in a 1D Photonic crystal (PC) consisting of nanometer sized silver particles embedded in LiNbO3 (metal/dielectric composite materials) are analyzed. By applying temperature with respect to plasma frequency the dielectric permittivity is determined for silver. The temperature increase will undergo a decrease in susceptibility of the material. Due to the variation in temperature, the tuning of a photonic band gap and polariton gap are analyzed thoroughly. These nanostructures are used in ultrafast photonic switches where the optical nonlinearity of third-order susceptibility is combined with light guiding.

Distribution of Silver (Ag) Nanoparticle in PVA/Ag Nanofiber Fabricated by Electrospinning Method

This research has successfully fabricated Ag nanoparticles and PVA/Ag nanofiber as antibacterial agents. The silver nanoparticles were synthesized using a chemical reduction method, while PVA/Ag nanofiber was successfully fabricated with silver nanoparticles and PVA polymer materials using electrospinning method. The chemical reduction method is an effective method for obtaining nanometer-sized silver particles, while electrospinning is one of the most efficient and inexpensive methods to produce nanofiber products. The silver nanoparticles and PVA/Ag nanofiber were characterized using instruments of XRD, SEM, EDX, and antimicrobial test for PVA/Ag nanofiber. In addition, through an X-ray diffraction characterization, the average size of silver nanoparticles was approximately 19.12 nm. Meanwhile, the SEM morphological analysis of PVA/Ag nanofiber has an average fiber diameter of 449.11 nm. The result of EDX analysis of PVA/Ag nanofiber showed the aggregation of silver nanoparticles in the range of polymer fibers shown by white clumps. In addition, the antibacterial test results on PVA/Ag nanofiber within 24 hours of incubation showed that the largest nanofiber zone of inhibition was in the diameter range of 0.9 cm. This case shows that PVA/Ag nanofiber has a relatively low antimicrobial power. This condition can be increased by reducing the possible impact of contamination from PVA/Ag nanofiber by the surrounding environment. Thus, the PVA/Ag nanofiber resulted in this study has a potential to be used as a wound dressing under optimal conditions.

Healing of burn wounds by topical treatment: A randomized controlled comparison between silver sulfadiazine and nano-crystalline silver.

Background:Silver sulfadiazine (SSD) has been the standard topical antimicrobial for burn wounds for decades. Recently, nanometer-sized silver particles are available which have high surface to volume ratio and remain effective even at a very low concentration and minimizes the chance for tissue toxicity due to silver. Hence, we conducted a randomized controlled trial to compare the effectiveness of topical SSD and nano-crystalline silver (AgNP) hydrogel in burn wounds management.Materials and Methods:Study was conducted in the Burn Unit of IPGME&R & SSKM Hospital Calcutta, from January 2011 to August 2012. Patients with 2° burn injury were randomly allocated to SSD and AgNP treatment group. Clinical assessments of burn wound were done on every week till 4th week and on completion of treatment.Results:Data for evaluation were obtained for 54 patients on SSD (2° deep-dermal cases 27) and 52 (2° deep-dermal cases 31) on AgNP treatment. Healing status of 2° deep-dermal burns was more satisfactory for AgNP group than SSD treatment at 4 weeks. Among patients receiving AgNP, 80.6% showed at least 50% healing of 2° deep-dermal wounds compared to 48.1% on SSD at 4 weeks (P = 0.001). The figures for complete healing at 4 weeks were, respectively, 4% and 0% (P = 0.116).Conclusions:AgNP can be an effective and superior alternative to SSD for burn wounds, particularly 2° deep-dermal burns. Healing can be expected, in general, in 6 to 8 weeks time, depending upon the extent of body surface involvement.

Novel Method of Incorporating Silver Nanoparticles into Natural Rubber Latex Foam

Silver nanoparticles (SNP) incorporated potassium oleate (KOL) soap by in situ reduction of silver nitrate by trisodium citrate (TSC) was described. Novel incorporation method of SNP into the natural rubber latex foam (NRLF) was successfully carried out by mixing 4 parts per hundred rubber (pphr) of SNP incorporated KOL soap in to the natural rubber latex (NRL) compound. UV-Visible spectrophotometer analysis, particle size analysis data and transmission electron micrograph analysis proved the modified KOL soap consisted of stable mono-dispersed nanometer size silver particles. SEM/EDX analysis of a latex film made out with modified NRL compound by SNP incorporated KOL soap shows nanosized silver particles inside it. Modified KOL and final product of modified NRLF by SNP incorporated KOL soap tested for antimicrobial properties against Escherichia coli (E. coli). The resultant KOL itself can inhibit Gram negative E. coli bacterium in a very strong manner. Inhibition of the same strain of E. coli bacterium by modified NRLF showed positive result.

Synthesis and characterization of nano silver based natural rubber latex foam for imparting antibacterial and anti-fungal properties

Synthesis and characterization of nanosilver based antimicrobial natural rubber latex foam (NRLF) is described. Silver nanoparticles were synthesized by reducing silver nitrate by tri-sodium citrate in an aqueous medium. UV–Vis spectrophotometer analysis, particle size analysis and transmission electron image analysis proved that the resultant silver nanocolloid was an aqueous dispersion consisting of stable nanometer size silver particles. Antibacterial activities were tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli (E. coli) bacteria, whereas antifungal activities were tested against Aspergilles niger (A. niger). It was found that the resultant NRLF samples inhibit the growth of the these bacteria and fungus in a very strong manner.

Silver Immobilization on Honeycomb-patterned Polyvinypyrrolidone thin Films via an Electroless Process

Honeycomb-patterned polyvinypyrrolidone (PVP) thin films coated with nanometer-sized silver particles were prepared using honeycomb-patterned polystyrene (PS) template films fabricated by casting a polystyrene solution under humid condition. Silver was first metallized on the patterned PS films via silver nitrate () reduction using tetrathiafulvalene (TTF) and a small amount of PVP as the reductant and dispersing agent, respectively. The effects of , TTF, and PVP solution concentrations during the reduction process in acetonitrile were determined to obtain a uniform silver-coated honeycomb-patterned PS film. Second, the silver-metallized patterned porous PS films were filled with high PVP concentration solutions via the spincoating process. Silver-coated patterned PVP films were obtained by peeling off the PVP layer from the template PS film after drying. The results show that the honeycomb-patterned PVP films uniformly coated with silver particles are conveniently obtained using the silver-coated patterned PS template, although the direct fabrication of these films using water droplets under humid conditions was not feasible because of the water solubility of PVP.

28.1: Invited Paper: Novel, Bright, Inorganic Electroluminescent Flexible Displays Comprising Ink Jet Printed Silver Back Electrodes

AbstractBright, flexible, paper substrate based electroluminescent displays have been realized using a combination of ink‐jet and screen printing. The segmented back electrodes were obtained by ink jet printing inks containing nanometer sized silver particles under computer control, thereby facilitating the fast fabrication of a wide range of highly detailed displays.

Nano-silver pulse treatments inhibit stem-end bacteria on cut gerbera cv. Ruikou flowers

Nanometer-sized silver (Ag +) particles (NS) are used in various applications as an anti-microbial. Effects of NS (2–5 nm diam.) pulse solution treatments on vase life of cut gerbera ( Gerbera jamesonii) cv. Ruikou flowers were investigated. Compared with the control [pulsed with deionised water (DI) and subsequently held in DI] pulsing for 24 h with 5 mg/L NS solution followed by holding in DI maintained water uptake and extended vase life. From in vitro and microscopy assessments, NS pulse treatment inhibited bacteria growth in the vase solution and at cut stem ends during the first 2 d of the vase period.

Nanometer Sized Silver Particles Embedded Silica Particles—Spray Method

Spherical shaped, nanometer to micro meter sized silica particles were prepared in a homogeneous nature by spray technique. Silver nanoparticles were produced over the surface of the silica grains in a harmonized manner. The size of silver and silica particles was effectively controlled by the precursors and catalysts. The electrostatic repulsion among the silica spheres and the electro static attraction between silica spheres and silver particles make the synchronized structure of the synthesized particles and the morphological images are revealed by transmission electron microscope. The silver ions are reduced by sodium borohydride. Infra red spectroscopy and X-ray photoelectron spectroscopy analysis confirm the formation of silver–silica composite particles. Thermal stability of the prepared particles obtained from thermal analysis ensures its higher temperature applications. The resultant silver embedded silica particles can be easily suspended in diverse solvents and would be useful for variety of applications.

Synthesis and photophysical study of silver nanoparticles stabilized by unsaturated dicarboxylates

Solution-phase synthesis of nanometer-sized silver particles is reported by sodium borohydride reduction of AgNO 3. Two isomeric dicarboxylates (sodium maleate and sodium fumarate) have been used as stabilizing agents. The dicarboxylate-stabilized silver nanoparticles are characterized by UV–vis spectroscopy, high-resolution transmission electron microscopy (HR-TEM) and fourier transform infrared (FT-IR) spectroscopy. A qualitative comparison is made between the UV–vis spectral characteristic of the SPR band and the simulated curve obtained from modified Mie's theory. Silver nanoparticles prepared using these two isomeric dicarboxylates show intense fluorescence in the visible region. DFT with hybrid functional (B3LYP)-based frequency (IR) calculation of both the dicarboxylates and the respective nanoparticles are in good agreement with the experimental IR frequency. On the basis of this calculation a model has been proposed for the stabilization of silver nanoparticles by these two isomeric dicarboxylate anions.

Assessment of nanocomposite photonic systems with the X-ray photoelectron spectroscopy

The chemical compositions of Ag-Er co-doped phosphate and silicate glasses were investigated with X-ray photoelectron spectroscopy with the purpose to identify the chemical state of silver. The analysis of the Ag 3d core lines show the presence of nanometer-sized silver particles in each of the annealed samples, even if these Ag 3d lines appear to be very different from each other. We explain these results as a different interaction of silver with the two glasses matrix, which leads to a different nucleation rate of the Ag clusters.

Novel and Facile Approach to the Fabrication of Metal-Patterned Dielectric Substrates

Both native and organic monolayer protected nanometer-sized silver particles were used to metallize patterns printed on glass and polyimide substrates by commercial permanent ink marking pens. The metal particles were selectively fixed onto the inked patterns by direct physical contact; the particles did not adhere to the free substrate surface. The patterns were made highly conductive by sintering or by mechanical buffing. The procedure allows the fabrication of patterned electrical circuits with minimal effort and a resolution of approximately 0.3 mm.

Size dependence of gradient and nongradient optical forces in silver nanoparticles

We examine the size dependence of gradient and nongradient contributions to the optically induced force on single, isolated nanometer-sized silver particles in water under plane-wave illumination. Using a recently developed method based on discrete-dipole approximation (DDA), we find that all contributions scale linearly with volume in this regime. This dependence can be rationalized by using semiempirical considerations based on the Mie-Debye theory. We also comment on a common approach to determining conservative and nonconservative force contributions on a single particle in an externally applied field. Our analysis suggests that the Mie-Debye theory cross sections cannot be used to evaluate conservative and nonconservative contributions to the force. Finally, we comment on aspects of the relationship between DDA and continuum-based treatments of optical force phenomena and find that inclusion of multiple scattering effects are essential to an understanding of the size dependence of the forces on mesoscopic particles.

Dithiocarbamate-Capped Silver Nanoparticles

Nanometer-sized silver particles were synthesized by using didecylamine dithiocarbamates as the protecting ligands. With control of the initial ligand-metal feed ratios, the core diameter of the resulting particles was found to vary from about 5 to 2.5 nm, as determined by transmission electron microscopic measurements. The core size dispersity was also found to decrease with increasing feed ratio. In UV-visible spectroscopic studies, the particle surface plasmon resonance peak diminished in intensity as the particle core size decreased, whereas in electrochemical measurements, smaller sized particles gave rise to well-defined quantized charging voltammetric features, in contrast to the featureless responses with the larger particles. Such single electron-transfer behaviors were consistent with those observed in STM measurements involving individual nanoparticles. Overall, this study provides an effective approach to the synthesis of stable nanometer-sized silver nanoparticles with interesting electronic and electrochemical properties.

In Situ Observation of Structural and Morphological Changes in Nanometer-sized Silver Particles on Graphite during Sublimation

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Exploitation of Electrostatic Field Force for Immobilization and Catalytic Reduction of o-Nitrobenzoic Acid to Anthranilic Acid on Resin-bound Silver Nanocomposites

A new solid-phase catalyst has been designed and reported here for the catalytic reduction of o-nitrobenzoic acid to anthranilic acid. Electrostatic field force helps immobilization, in turn deposition of silver nanoparticles onto solid resin surfaces and reduction of o-nitrobenzoic acid through effective catalysis. While characterization of catalyst particles has been performed by different physical methods (XRD, XPS, SEM, TEM, and EDX) in a worthwhile fashion, selective reduction of o-nitrobenzoic acid has also been achieved conveniently (approximately 95%). Different thermodynamic parameters for the reduction reaction have been presented from varied experimental conditions. Novelty of this work lies with the catalytic efficiency of nanometer size silver particles immobilized solid-phase matrix for one step synthesis of anthranilic acid over bulk silver.

Photochemical Synthesis and Multiphoton Luminescence of Monodisperse Silver Nanocrystals

A rapid, photochemical solution-phase synthesis has been developed for the production of monodisperse, nanometer-sized silver particles. The stabilizer used in the synthesis can be used to control the average diameter of the particles over a range from 1 to 7 nm. The same reaction mixture can also be employed to deposit patterns of nanoparticles with a laser via multiphoton absorption. The particles exhibit strong multiphoton absorption-induced luminescence when irradiated with 800-nm light, allowing emission from single nanoparticles to be observed readily.