Silica Xerogel Supported Silver Nanoparticles via Tin-Seeded Reduction for Iodine Capture

Abstract

Supported metal nanoparticles play a critical role in catalysis, environmental remediation, and biomedical applications due to their high surface area to volume ratios at sizes between 1–10 nm. We investigated the formation of silver nanoparticles (AgNPs) on silica xerogel supports using a tin-seeded reduction method. Silica xerogels were selected for their high surface area, sorption capacity, and stability, with silanol groups facilitating strong interactions with AgNPs. Tin(II) acetate was used to sensitize the silica surface, creating nucleation sites for silver reduction. Upon exposure to silver nitrate, Sn²⁺ was oxidized to Sn⁴⁺, and Ag⁺ was reduced to elemental silver, forming well-dispersed AgNPs. The size and distribution of AgNPs were influenced primarily by silver precursor concentration rather than tin concentration. Higher silver nitrate concentrations increased particle size and aggregation, while increased tin acetate concentrations enhanced the number of nucleation sites but not particle size. Solvent choice also affected silver loading, with methanol for tin and ethanol for silver leading to higher silver loading. Characterization by SEM, TEM, XRD, and XPS confirmed successful nanoparticle formation and good size control. AgNP-loaded silica xerogels showed high iodine adsorption capacity, indicating potential use in nuclear waste remediation.