Rattle-type Au@TiO2 hollow microspheres with multiple nanocores and porous shells and their structurally enhanced catalysis

A simple and flexible strategy is presented to fabricate the rattle-type hollow microspheres of Au@TiO2 based on multi-step template-deposition and surface-protected etching method. The Au nanoparticles are highly dispersed inside the TiO2 hollow microspheres, and the TiO2 shell layer is of porous nanostructure and permeable for chemical species. The size of Au nanoparticles and the thickness of TiO2 shells are tunable. Such rattle-type hollow spheres show the structurally enhanced activity and durability of catalytic performance in catalytic reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride, which is attributed to the high dispersivity of Au nanoparticles inside the hollow spheres with porous shells. This general strategy can also be utilized to prepare rattle-type TiO2 hollow microspheres with other noble metal nanocores. These noble metals@TiO2 nanorattles are not only novel nanoreactors but also potential photocatalysts due to the porous TiO2 loaded with noble metal nanoparticles and hence expected to find important applications in the areas such as catalysis and chemical and biological sensing.