Silver nanoparticles on carboxyl-functionalized Fe3O4 with high catalytic activity for 4-nitrophenol reduction

Ag nanoparticles deposited on polymer-coated magnetic Fe3O4 were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) equipped with an energy dispersive spectroscope (EDS), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The magnetic and suspension properties of the nanoparticles were investigated by monitoring the change of absorbance versus time at 560 nm. The nanocomposites showed high catalytic activity in the reduction of 4-nitrophenol by NaBH4 (with conversion of 100% in 10 s). To the best of our knowledge, this is the shortest time for the conversation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) reported in the literatures, so far. The turnover frequency (TOF) is 17.06 min(-1), much larger than those of other catalysts in the literatures. Furthermore, the nanoparticles could be easily recovered by a magnet and the strong catalytic activity was well maintained after three cyclic treatments.