The mechanisms of formation and growth of silver nanoparticles (NPs) in aqueous electrolytes are studied following the extinction plasmonic features using UV-Visible spectroscopy and with the aid of theoretical methods. Silver NPs are produced by using the reaction between silver (I) and 1, 4- para-hydroquinone under different experimental conditions (varying reactive species concentration, nature and concentration of ligands, stabilization agents and co-reactants, etc.). NP extinction spectra were taken in the 200-1100 nm wavelength range during the reaction time. The final products morphology was determined using TEM. Theoretical calculations with Mie?s theory were performed as a reference to analyze the changes of global NP morphology. The analysis performed in the present work relies mainly on the information provided by spectroscopy rather than TEM, since the first provides information on the whole sample while the second is limited to selective fields taken from the global sample. The analysis indicates that formation and growth of silver NPs take place by a mechanism involving a progressive nucleation as well as an autocatalytic surface growth. The effect of different synthetic variables (such as the chemical nature of the metallic precursor, hydroquinone concentration, stabilization agents and ligands) on the NP?s nucleation and growth are also analyzed. A very important dependence of the NP?s final morphology on the procedure of mixing of reactants was found connected to the metallic precursor nature. Ammonia solutions containing strong stabilization agents are demonstrated to help to control shape/size by quenching the autocatalytic surface growth.
