Influence of adsorption of reactants on preparation of silver nanoparticles by adsorption phase synthesis

Three reaction systems were selected to investigate the influence of reactants distributed in a bulk or in an adsorption layer on the preparation of silver nanoparticles. Reactant distribution in three systems was measured by iodometric, Volhardʹs and conductivity methods, respectively. Results show that the reactants in system I and II both distributed mainly in the bulk and the adsorption layer could not affect the reactant distribution. In system III, both the formation and the change of the adsorption layer could influence much on the reactant distribution. When the adsorption layer formed gradually in system III, mass percent of NaOH adsorbed on SiO2 changed from 25 to 60%. With amount of reactant in the adsorption layer increasing, reaction region transferred gradually from the bulk to the adsorption layer, which led to more homogeneous Ag particles with smaller size on SiO2 surface. Due to the significant inhibition of the nanoreactor, the size of Ag particles grew in the adsorption layer was below 5 nm.