Large-scale synthesis and self-organization of silver nanoparticles with Tween 80 as a reductant and stabilizer

Abstract

Tween 80 (polysorbate 80) has been used as a reducing agent and protecting agent to prepare stable water-soluble silver nanoparticles on a large scale through a one-pot process, which is simple and environmentally friendly. Silver ions can accelerate the oxidation of Tween 80 and then get reduced in the reaction process. The well-ordered arrays such as ribbon-like silver nanostructures could be obtained by adjusting the reaction conditions. High-resolution transmission electron microscopy confirms that ribbon-like silver nanostructures (approximately 50 nm in length and approximately 2 μm in width) are composed of a large number of silver nanocrystals with a size range of 2 to 3 nm. In addition, negative absorbance around 320 nm in the UV-visible spectra of silver nanoparticles has been observed, probably owing to the instability of nanosized silver colloids.

Figure 1

XRD patterns of the samples prepared from the mixtures. The mixtures include 50 and 100 mg AgNO₃, respectively.

Figure 2

XPS spectra of the Tween 80-stablized silver nanoparticles. (a) The survey spectrum and the close-up spectra of (b) Ag 3d, (c) C 1s, and (d) O 1s. Red and green lines represent deconvolution of the spectra into Gaussian bands.

Figure 3

FT-IR spectra. Ag NPs obtained from the system added with 70 mg AgNO₃ and pure Tween 80.

Figure 4

Schematic illustration of the proposed mechanism for the formation of Tween 80-stabilized silver nanoparticles.

Figure 5

UV-vis spectra of silver aqueous solutions obtained dry and wet systems. The (a) dry and (b) wet systems at 100°C. 1, 2, 3, 4, 5 respectively correspond to the UV-vis spectra of systems added with 10, 20, 50, 70, and 100 mg of AgNO₃. The inset is the diagram of wavelength of absorption peaks versus its corresponding AgNO₃ amount.

Figure 6

TEM images of silver particles. These particles were synthesized in the wet systems added with (a) 10, (b) 20, (c) 50, and (d) 100 mg of AgNO₃ at 100°C for 3 days. The insets in (b) and (c) are the high-resolution transmission electron microscopic image and SAED patterns taken from a single particle.

Figure 7

PSDs of silver particles. Ag particles were synthesized in the wet systems added with (a) 10, (b) 20, (c) 50, and (d) 100 mg of AgNO₃ at 100°C for 3 days.

Figure 8

UV-vis spectra of aqueous solutions of silver nanoparticles synthesized at different temperatures. (a) and (c) 90°C, (b) and (d) 110°C. The spectra of (a) and (b) were acquired on a UV-3150 spectrophotometer, while (c) and (d) on a diode-array spectrophotometer.

Figure 9

TEM images of silver nanoparticles obtained in wet systems. (a) 20, (b) 50, and (c) 100 mg of AgNO₃ at 90°C; (d) 20, (e) 50, and (f) 100 mg of AgNO₃ at 110°C for 3 days.

Figure 10

TEM images of silver nanoparticles. Obtained in (a) wet systems; (b) dry system with 50 mg of AgNO₃ at 90°C for 1 day. (c) to (f) are the images with higher magnification. The insets are the ED patterns of the ribbons.

Figure 11

Simulated absorption curves of silver nanoparticles obtained with different AgNO₃concentrations.