Synthesis of Highly Monodisperse Citrate-Stabilized Silver Nanoparticles of up to 200 nm: Kinetic Control and Catalytic Properties

Abstract

Highly monodisperse sodium citrate-coated spherical silver nanoparticles (Ag NPs) with controlled sizes ranging from 10 to 200 nm have been synthesized by following a kinetically controlled seeded-growth approach via the reduction of silver nitrate by the combination of two chemical reducing agents: sodium citrate and tannic acid. The use of traces of tannic acid is fundamental in the synthesis of silver seeds, with an unprecedented (nanometric resolution) narrow size distribution that becomes even narrower, by size focusing, during the growth process. The homogeneous growth of Ag seeds is kinetically controlled by adjusting reaction parameters: concentrations of reducing agents, temperature, silver precursor to seed ratio, and pH. This method produces long-term stable aqueous colloidal dispersions of Ag NPs with narrow size distributions, relatively high concentrations (up to 6 × 1012 NPs/mL), and, more important, readily accessible surfaces. This was proved by studying the catalytic properties of as-synthesized Ag NPs using the reduction of Rhodamine B (RhB) by sodium borohydride as a model reaction system. As a result, we show the ability of citrate-stabilized Ag NPs to act as very efficient catalysts for the degradation of RhB while the coating with a polyvinylpyrrolidone (PVP) layer dramatically decreased the reaction rate.

Modeling the Optical Responses of Noble Metal Nanoparticles Subjected to Physicochemical Transformations in Physiological Environments: Aggregation, Dissolution and Oxidation

“…Interestingly, in this case, the maximum absorbance value constantly increases as NP size increases, which can be explained by the higher amount of metal atoms present in the solutions with larger NPs. These results are more representative of the growth mechanism of NPs by monomer addition used in many synthetic strategies [45][46][47]. Thus, when the growth process takes place via the incorporation of monomer from the solution (the total number of NPs in solution remains unaltered), a constant increasing of maximum extinction should be observed by UV-vis characterization ( Figure 3).…”

Synthesis and immobilization of silver nanoparticles on aluminosilicate nanotubes and their antibacterial properties

“…To the best of our knowledge, the formation and stabilization of AgNPs could only be achieved through the use of certain reducing and stabilizing agents, and even then obtaining small particles as small as 3 nm is quite challenging (Bastús et al 2014;Pinto et al 2010;Leo et al 2013). This is the first synthetic route that allows synthesis of highly stable small-sized AgNPs without any chemicals and simultaneous synthesis of novel nanotubebased nanohybrid architectures.…”

Facile Method for the Synthesis of Copper Nanoparticles Supported on the Organoclay Material

“…Studies have shown that the size, morphology, stability and chemical and physical properties of the metal nanoparticles are influenced strongly by the experimental conditions, the kinetics of interactions of metal ions with reducing agents, and adsorption processes of stabilizing agent with metal nanoparticle [14]. The most known conventional chemical route for the synthesis of nanoparticles involved the reduction from the appropriate salt solution, excess reducing agents such as sodium citrate [15] or NaBH 4 [16] [17] and the stabilizing agent to stabilized nanoparticles in solution in order to prevent aggregation. The stabilization, in general, takes place by the absorption of electric charges on the surface, leading to a repulsion of the nanoparticles as long as a critical distance maintained [18].…”