Effect of NH3 on the Nature of Ag-Nanoparticles Prepared via the Borohydride Reduction

Silver nanoparticles (Ag⁰-NPs) prepared via the Creighton procedure (chemical reduction by BH₄⁻) from the Ag₂SO₄ and AgNO₃ precursors exhibit significant differences in sizes, crystal structures, and catalytic properties, even though neither sulfate nor nitrate is a good ligand for Ag⁺. Furthermore, the addition of NH₃ before the reduction of silver ions into Ag⁰ nanoparticles leads to a marked increase in nanoparticle size and alters both their crystallographic features and catalytic performance. These results highlight that even seemingly minor modifications in solution composition, such as the nature of the counterion or the presence of simple ligands like ammonia, can profoundly affect the nucleation and growth processes of Ag⁰ nanoparticles. Such simple solution-phase components, often overlooked, significantly influence the final size, morphology, and properties of metal nanoparticles.