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.