Ligand-modified mesoporous silica SBA-15/silver hybrids for the catalyzed reduction of methylene blue

Abstract

Mesoporous silica SBA-15 was prepared and functionalized by (3-glycidyloxypropyl)trimethoxysilane in order to bind 2-aminothiazole and aminopropyl-triazole ligands. These groups were immobilized through two distinct chemistry routes: reaction of epoxy with amine resulting in AMT-SBA-15 for the former, and epoxy ring opening followed by 1,3-dipolar cycloaddition click reaction providing Tr-SBA-15, for the latter. These ligand-functionalized SBA-15 materials served as reactive platforms for the in situ deposition of silver nanoparticles from the reduction of silver nitrate. The silver-decorated hybrid Ag/AMT-SBA-15 and Ag/Tr-SBA-15 samples, as well as their precursors, were characterized by X-ray diffraction (XRD), N₂ adsorption–desorption isotherms, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The silver-decorated hybrid materials were evaluated as catalysts for the reduction of methylene blue; the results showed excellent catalytic efficiencies with reduction rate constants of 14.3 × 10⁻³ and 9.4 × 10⁻³ s⁻¹ for Ag/Tr-SBA-15 and Ag/AMT-SBA-15, respectively. These values are comparable or higher than those claimed in the literature for similar application.