Surfactant free synthesis of gold nanoparticles within meso-channels of non-functionalized SBA-15 for its promising catalytic activity

Abstract

This work reports surfactant free synthesis of monodisperse gold (~2.3nm) particles confined within the pore channels of ordered hexagonal mesoporous silica SBA-15 (Au/SBA-15) by a modified wetness impregnation method. The synthesized Au/SBA-15 composite showed excellent catalytic activity towards the reduction of different wastewater organic pollutants as well as their mixtures under ambient conditions. The composite was also investigated for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). XRD, UV-DR visible spectroscopy, N2 adsorption-desorption analysis, ICP-AES, FT-IR spectroscopy, and TEM were employed to characterize the catalyst samples. The wetness impregnation method followed by a washing step with dilute aqueous NH3 was found to be an effective route to synthesize stable and highly dispersed small gold nanoparticles (Au NPs) within the mesopore channels of SBA-15. All the catalytic reactions followed pseudo-first-order kinetics and catalytic efficiency of the composite was found almost constant up to five cycles.