One-step fabrication of gold nanoparticles-silica composites with enhanced catalytic activity

A fast and simple one-step method for the fabrication of stable gold nanoparticles-silica composites by using 1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexacosane(azacryptand) as a molecular anchor between nanoparticles and silica as well as reductant and stabilizer in the formation of the nanoparticles is reported. Gold nanoparticles-coated silica materials can be fabricated by mixing HAuCl4 aqueous solution with the aqueous mixture of azacryptand and silica materials such as submicrometer silica particles and silica gel. The prepared nanoparticles-coated silica gel can effectively catalyze reduction of 4-nitrophenol by sodium borohydride in aqueous solution.