A highly reactive and magnetic recyclable catalytic system based on AuPt nanoalloys supported on ellipsoidal Fe@SiO2

A facile method has been developed for the synthesis of highly active and well-defined AuPt nanoalloys supported on the surface of ellipsoidal Fe@SiO2 nanoparticles. This method involves the loading of Pt NPs on the Fe2O3@SiO2 nanocapsules via Sn2+ linkage and reduction, then in situ fabrication of Au nanoparticles by the galvanic replacement reaction between Au and Pt, and finally calcination and reduction to convert the nonmagnetic Fe2O3 to Fe core with high saturation magnetization. XRD and XPS analysis demonstrates the alloy structure of AuPt nanoparticles in the final samples. The obtained Fe@SiO2/AuPt samples exhibit a remarkably higher catalytic activity in comparison with the supported monometallic counterparts toward the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. The catalyst can be reused for several cycles with convenient magnetic separation.