Synthesis of novel two-phase Co@SiO₂ nanorattles with high catalytic activity.

Noble metal nanocatalysts with remarkable catalytic properties have attracted much attention; however, the high cost of these materials limits their industrial applications. Here, we design and prepare Co@SiO2 nanorattles as a mixture of hcp-Co and fcc-Co phases as a substitute. The nanorattles exhibit both superior catalytic activity and high stability for the reduction of p-nitrophenol. The reduction rate nearly follows pseudo-first-order kinetics, and the reaction rate constant is as high as 0.815 min(-1) and is maintained at 0.565 min(-1) even after storing for one month, which is higher than that reported for noble metal nanocatalysts. Such an excellent property can be attributed to the novel two-phase composition and rattle-type structure.