A simple green synthesis of pure and sterling silver nanoparticles via pulsed laser ablation in deionized water: characterization and comparison

Abstract

Pure silver (Ag) and its alloy nanoparticles (NPs) with intense and tunable SPR bands in the visible region are widely exploited for biosensors, information storage, and solar energy systems. Pure Ag and Sterling silver (Ag92.5Cu7.5) NPs were synthesized by the laser ablation method in deionized water using a pulsed Nd:YAG laser. The prepared NPs were characterized and compared for their structural, morphological, and optical properties. The x-ray diffraction (XRD) and selected area electron diffraction (SAED) results revealed that the NPs have polycrystalline nature with five lattice directions. The diffraction peak positions for Ag92.5Cu7.5 NPs exhibited an average redshift of 0.1 ̊ compared to pure Ag NPs due to the presence of copper atoms in the composite crystal unit cell structure. The formation of spherical NPs with an average size of 9.1 nm and 8.4 nm for Ag and Ag92.5Cu7.5 NPs was confirmed using transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). It was found that the concentration of synthesized Ag92.5Cu7.5 alloy NPs was considerably higher than that of pure Ag NPs. Going from pure to alloy silver NPs, the wavelength of surface plasmonic resonance (SPR) peak shifted from 400 nm to 395 nm. The UV-vis absorption spectra at different aging times revealed that pure Ag colloidal solution is relatively stable. Both colloidal solutions exhibited a similar pattern of photoluminescence (PL) emission spectra with peaks in the blue region.