Silica-supported Au@hollow-SiO2 particles with outstanding catalytic activity prepared via block copolymer template approach

Abstract Catalytically active Au@hollow-SiO 2 particles embedded in porous silica support (Au@hollow-SiO 2 @PSS) were prepared by using spherical micelles from poly(styrene)- block -poly(4-vinyl pyridine) block copolymer as a sacrificial template. Drastic increase of the shell porosity was observed after pyrolytic removal of polymeric template because the stretched poly(4-vinyl pyridine) chains interpenetrating with silica shell acted as an effective porogen. The embedding of Au@hollow-SiO 2 particles in porous silica support prevented their fusion during pyrolysis. The catalytic activity of Au@hollow-SiO 2 @PSS was investigated using a model reaction of catalytic reduction of 4-nitrophenol and reductive degradation of Congo red azo-dye. Significantly, to the best of our knowledge, Au@hollow-SiO 2 @PSS catalyst shows the highest activity among analogous systems reported till now in literature. Such high activity was attributed to the presence of multiple pores within silica shell of Au@hollow-SiO 2 particles and easy accessibility of reagents to the catalytically active sites of the ligand-free gold surface through the porous silica support.