Role of pH in the synthesis of 3-aminopropyl trimethoxysilane stabilized colloidal gold/silver and their alloy sols and their application to catalysis

► Synthesis of nano-alloy dispersions of Au and Ag in aminosilicate sol. ► pH conditions on chemical stability of Au, Ag and their alloy sols were optimized. ► The stable alloy sols catalyze the reduction of 4-nitrophenol to 4-aminophenol. ► Catalytic rate constants were evaluated from UV-visible spectroscopy.