Deposition of silver nanoparticles on organically-modified silica in the presence of lignosulfonate

Abstract

It is shown that the chemical reduction of silver ions by lignosulfonate (LS) in a mixed aqueous–organic solvent produces silver nanoparticles (AgNPs). If, additionally, spherical silica (SiO₂) (surface-functionalized with various organic groups) is introduced to the reaction mixture, the LS-stabilized Ag-NPs are deposited on the surface of the silica spheres, forming a SiO₂–LS–AgNPs hybrid material. The efficiency of the process is found to depend significantly on both the polarity of the organic solvent and the hydrophobicity of the SiO₂-grafted functionalities. The most effective synthesis was in a mixed dimethylformamide–water solvent with octadecylsilane-functionalized SiO₂. It is concluded that hydrophobic forces are essential for the successful coupling of LS–AgNPs with the surface of the modified silica. The formation of LS–AgNPs was monitored by UV-Vis spectroscopy, and the properties of the final hybrid materials were determined by EDS, elemental analysis, NIBS, TGA colorimetric analysis and HRTEM techniques. The resulting SiO₂–LS–AgNPs hybrids were also used as SERS substrates with Rhodamine 6G as a test molecule.