Formation Of Ag Nanowires Research Articles

Synthesis and Reduction Processes of Silver Nanowires in a Silver(I) Sulfamate-Poly (Vinylpyrrolidone) Hydrothermal System.

Silver (Ag) nanowires, as an important one-dimensional (1D) nanomaterial, have garnered wide attention, owing to their applications in electronics, optoelectronics, sensors, and other fields. In this study, an alternative hydrothermal route was developed to synthesize Ag nanowires via modified reduction of Ag+. Silver sulfamate plays an important role in the formation of Ag nanowires via controlled release of free Ag+. Results of controlled experiments and characterizations such as UV-vis spectroscopy, FTIR, XPS, and 1H NMR revealed that sulfamic acid does not function as a reductant, supporting by the generation of free Ag+ instead of Ag nanostructures in hydrothermally treated silver sulfamate solution. The initial reduction of Ag+ was induced by the combination of poly (vinylpyrrolidone) (PVP) end group and degradation products. This phenomenon was supported by abundant free Ag+ in the mixed preheated silver sulfamatic and preheated PVP aqueous solutions, indicating a second and distinct Ag+ autocatalytic reduction. Thus, the roles of different reagents and Ag+ reduction must be studied for nanomaterial syntheses.

Formation of Ag nanowires in the presence of tannic acid

Silver nanowires (AgNWs) have received considerable attention from both research in industry and academia due to their exceptional practicable applications in various electronic devices. In this work, pure AgNWs in the absence of nanoparticles are synthesised through chemical reduction method at low temperature 80 °C. AgNWs are produced based on the reaction of a reducing agent of tannic acid and a capping agent of polyvinylpyrrolidone (MW ≈ 1,200,000). The purity of the as-prepared AgNWs is improved in the presence of both chemical reactants. The controllable morphologies and sizes make the AgNWs grown steadily up to ∼30±2 μm in length with up to ∼58±1.8 nm in diameter. To enhance the yield of AgNWs, variations in the silver nitrate precursor (AgNO3) concentration in the synthesis of AgNWs are highlighted. The properties of the synthesised AgNWs are characterised through scanning electron microscopy (SEM), photoluminescence spectroscopy and UV–visible absorption spectroscopy. The overall properties of the AgNWs in terms of scattered light intensity and the transmittance of optical responses were largely improved as compared to other reported studies.

Voltage- and temperature-dependent electrical behavior of gap-type Ag–Ag2S–Pt atomic switch

The voltage- and the temperature-dependent electrical behavior of a gap-type Ag–Ag2S–Pt atomic switch is theoretically investigated. The electrical tunnel current passing through the switch is calculated and the growth of Ag nanowires between two electrodes is simulated. Our calculations show the switching time (the time that is required to decrease the resistance of switch below the resistance quantum RQ ≈ 6.5 kΩ) exponentially decreases as the applied voltage increases that agrees very well with experimental findings. Furthermore, we assumed the Ag2S layer is a few atomic layer thick so the diffusion time of Ag+ ions within the Ag2S layer can be neglected compared to the formation of Ag nanowires. As a result, the switching time decreases exponentially as temperature increases. The switching time is calculated while different DC voltages are applied to the switch over temperature range of T = 300–350 K. The results imply both of the voltage- and the temperature-dependent behavior of the gap-type Ag–Ag2S–Pt atomic switch is dominated by the Coulomb blockade (CB) effect of Ag nanowires as electrons require energy to overcome the CB energy of Ag nanowires to sustain the growth of Ag nanowires.

Synthesis of high yield silver nanowires for transparent flexible conductor applications

In the present study, we demonstrate a solution-phase synthesis of silver nanowires (AgNWs) using poly vinyl pyrrolidone (PVP). NaCl was added as a precursor to the reaction for controlling the free Ag+ions concentration during the formation of initial Ag seeds. By controlling the experimental conditions, the Ag nanostructures can be transformed from nanoparticles to nanowires. Field emission scanning electron microscopy results show that AgNWs of diameter ∼50−80 nm and length ∼5−30 μm can be achieved. UV−Visible absorption spectroscopy and energy dispersive spectroscopy results indicate the formation of Ag nanowires in highly pure phase. In addition, thin film of AgNWs has been fabricated on polyethylene terephthalate (PET) substrate to form a flexible transparent electrode. The optical and electrical studies on AgNWs coated PET substrate show the formation of transparent and electrically continuous network of AgNWs with a resistance of ∼60 Ω/sq. and maximum total transmittance (T) of ∼86%.

Formation of Ag nanowires on graphite stepped surfaces. A DFT study

We investigate the feasibility of obtaining silver nanowires on graphite stepped surfaces theoretically, using density functional theory calculations. Three layer slabs are used to model graphite surfaces with and without defects. Adsorption energies for Ag atoms on graphite surfaces were calculated showing the preference of Ag adatoms to locate on the steps, forming linear structures like nanowires. An analysis of the charge densities and projected densities of states for different structures is also performed.