Confined Generation of Homogeneously Dispersed Au and SnO2 Nanoparticles in Layered Silicate as Synergistic Catalysts.

With the aid of the confined conversion of layered silicate RUB-15, homogeneously dispersed Au and SnO2 nanoparticles (NPs) were generated in the confined layer space of RUB-15. The Au-SnO2/SiO2 composite was obtained with the structure that ultrafine Au and SnO2 NPs were supported on SiO2 lamellas. Benefited by the Sn(II)-assisted in situ reduction strategy, Au NPs were highly uniformed and evenly distributed in/on the RUB-15. This Au-SnO2/SiO2 composite was employed as a catalyst to the reduction of 4-nitrophenol showing excellent catalytic activity. The catalytic rate constant at room temperature was calculated to be 6.64 min-1, which was dramatically higher than that of Au/SiO2 composite produced by reduction with hydrazine hydrate on the same support of layered silicate RUB-15. The interaction between Au and SnO2 NPs increased the electron density around Au NPs, which was demonstrated to be an essential factor to the excellent catalytic activity of the Au-SnO2/SiO2 composite. The simple and universal synthesis method afforded precise control over the size/spatial arrangement of Au and SnO2 NPs on SiO2 lamellas. The high activity of the Au-SnO2/SiO2 composite demonstrated that the strategy used in this study has good potential application prospect. Furthermore, this work provided new perspective on the catalysis mechanism to the metal/semiconductor synergistic catalyst system.