Optical and Structural Characterization of Honeycomb-Like Ag2S Nanoparticles by a Simplified and Stable Wet Chemical Synthesis Method

Abstract

The goal of this paper is to present a stable and new formulation route for the synthesis of silver sulfide nanoparticles with stoichiometric Ag2S composition in aqueous solution. The structural, optical, and morphological properties of Ag2S nanoparticles were studied by using characterization techniques such as ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy and x-ray photoelectron spectroscopy (XPS). From the UV–Vis spectrum, the direct and indirect energy gap values of 3.56 and 1.89 eV were calculated, related to direct and indirect transitions of electrons, as an estimation of bandgaps. Also, an optical band gap shift with respect to bulk bandgap is observed reported in the literature and is related to nanoparticle size decrease. Furthermore, from the high-resolution transmission electron microscopy micrograph an orthorhombic crystallographic structure was determined with lattice parameters 4.77 × 6.92 × 6.88 A and the nanoparticle surface showed a honeycomb-like interference pattern. Finally, the expected chemical composition was proved by the low- and high-resolution XPS spectra.