Home – Home – Jornals – Chemistry for Sustainable Development 2020 number 1

The reduction of silver nitrate in polyols in the presence of hydroxyethylated carboxylic acid as a stabilizer was investigated. The effect of synthesis conditions, in particular temperature, synthesis time, concentrations of silver salt, stabilizer, and sodium hydroxide, on the structural characteristics of the synthesized particles was studied by means of electron microscopy and X-ray diffraction. It was shown that large polyhedra 200-800 nm in size are formed in the system in the absence of the stabilizer, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MEEAA). In the presence of MEEAA, silver nano- and microplates with the sizes ranging from 10-20 nm to 1 µm are formed, depending on synthesis conditions. The optimal reaction conditions were determined for obtaining silver plates 100-500 nm in size, with the dominating 200-300 nm fraction: temperature, 100 °C; synthesis time, 1 h; MEEAA to Ag molar ratio, 3 : 1. The type of polyol was shown to affect both the morphology of the resulting particles and the fraction of plates and polyhedra in the final product. Thus, the fraction of polyhedra with respect to the plates increases when passing from ethylene glycol to triethylene glycol and propylene glycol. The effect of the alkaline reagent (NaOH) on the composition, size, and morphology of reduction products was studied. It was shown that the rate of silver ion reduction increases significantly in the presence of NaOH, which allows carrying out the process at room temperature. At a molar ratio of NaOH to Ag equal to 4 : 1, nanoplates 10-20 nm in size are formed. As-synthesized silver micro- and nanoplates can be used in the development of conductive materials, including pastes and inks for printed electronics.