Preparation of silver nanoparticles from silver(I) nano-coordination polymer

Abstract

Nanorods of two-dimensional organometallic coordination polymer, [Ag(μ₄-DPOAc)]_n (1) [DPOAc⁻ = diphenylacetate], has been synthesized by the reaction of potassium diphenylacetate (DPOAcK) and AgNO₃ by sonochemical process. Reaction conditions, such as the concentration of the initial reagents played important roles in the size and growth process of the final product. Silver nanoparticles were synthesized from nanorods of compound 1. These nano-coordination polymer and nanoparticles were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Thermal stability of nano and crystal samples of compound 1 were studied and compared with each other.

Introduction

Silver has been extensively used in a variety of applications such as catalysis, electronics, photonics and photography due to its unique properties. For example, silver has the highest electrical conductivity, thermal conductivity and reflectivity of all metals [1]. Several methods can be applied to synthesize silver nanoparticles with well-defined shapes. The majority of the more straightforward approaches are based on the reduction of silver nitrate by sodium borohydride [2] or sodium citrate [3]. Some of the more diverse methods previously used include microwave plasma synthesis [4], electrolysis of Ag salts [5], rapid expansion of supercritical solvents [6], [7], microemulsion [8], and photoreduction of Ag ions [9], [10]. Recently in the last few years several methods for synthesis of silver nano structures have been developed too, which are: (a) synthesis of fine silver powder with a particle size range of 50–1000 nm in a mechanochemical process by inducing a solid-state displacement reaction between AgCl and sodium [11], (b) synthesis of long silver nanowires with lengths of more than 50 mm, some even more than 100 mm, and average diameters of about 80 nm at room temperature by a simple and fast process derived from the development of photographic films [12], (c) synthesis of metallic silver by direct hydrogen reduction of Ag₂S in basic slurry under hydrothermal conditions [1] and (d) in situ preparation of Ag nanoparticles from the hydrolytic decomposition of silver triethanolamine (TEA) complexes that lead to the formation of spherical metallic silver particles with mean diameter of 8 nm well adsorbed onto the bacterial cellulose fibrils [13]. In recent years silver(I) complexes have found application as precursors for Chemical Vapor Deposition (CVD) [14], [15], [16], [17]. As mentioned above preparation of silver nanoparticles from silver complexes reported by Barud et al. [13], but the use of silver coordination polymers (CPs) or silver nano-coordination polymers (NCPs) to prepare silver nano structures is sparse [18]. NCPs are generally synthesized by exploiting the insolubility of the particles in a given solvent system. Wang et al. reported the first synthesis of NCP in 2005 [19]. They isolated monodisperse spheres of approximately 420 nm in diameter, taking advantage of the very low solubility in water of the product from the reaction between the initial precursors. We used this method to prepare NCPs by sonochemical process [20], [21], [22], [23], [24], [25]. Continuing our previous work on CPs [26], [27], [28], [25], [29], [30], [31], synthesis of Ag^I NCP by sonochemical process and use this precursor to fabricate silver nanoparticles with oleic acid as a surfactant were reported.