The preparation of Ag/mesoporous silica by direct silver reduction and Ag/functionalized mesoporous silica by in situ formation of adsorbed silver

Mesoporous silica (MS) with large pores and thiol functionalized mesoporous silica (TFMS) were synthesized. ²⁹Si MAS NMR confirmed the functionalization of MPTMS on the surface of mesoporous silica. Silver nanoparticles were prepared by two methods: (1) direct reduction of Ag⁺ ions with NaBH₄ in aqueous AgNO₃ solution containing MS, (2) in situ reduction of Ag⁺ ions adsorbed on TFMS with NaBH₄. The characteristics of products from both methods were compared using SAXRD, TEM, and N₂ adsorption-desorption. Ag nanoclusters were mostly confined and dispersed in the channels of the TFMS and their sizes were under 6 nm. However, Ag nanoparticles on the MS formed outside the mesoporous channels rather than within them.