Thermally robust silica-enclosed Au25 nanocluster and its catalysis

Well-defined gold nanoclusters with average size less than 2 nm have emerged as a new and novel catalyst. The gold nanocluster loaded on the oxide surface usually aggregates to larger particles at high temperature (> 300 °C), which is caused by the removal of the surface ligands. We herein present a novel method to prepare Au 25 cluster catalyst (∼1.3 nm) with high thermal stability (up to 400 °C). Au 25 @SiO 2 is synthesized via a co-hydrolyzing reaction of Au 25 [SC 3 H 6 Si(OCH 3 ) 3 ] 18 and tetraethyl orthosilicate, and then it is treated at different temperature (e.g., 200, 300, 400 °C) in air to remove the organic ligands. Au 25 @SiO 2 is well characterized by transmission electron microscopy, ultraviolet-visible spectroscopy and diffuse reflectance UV-vis spectroscopy. Further, the Au 25 @SiO 2 catalysts are investigated in the hydrogenation of p -nitrophenol into p -aminophenol.