MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS, vol.23, no.12, pp.5745-5758, 2017 (SCI-Expanded)
A simple, economic and one pot synthetic protocol was followed to synthesize Fe3O4 nanostructures using partial oxidation co-precipitation method under aerobic conditions. After synthesis, the nanostructures were coated with tetraethyl orthosilicate for stabilization purpose. Later on, these nanostructures were characterized by fourier transformed infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, electron dispersive X-ray spectroscopy and atomic force microscopy to examine their size, shape and crystalline structure. The synthesized SiO2/Fe3O4 nanostructures with fine semi-spherical textures showed high heterogeneous catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol using sodium borohydride (NaBH4) under microwave radiations. The effect of Different parameters such as concentration of reducing agent (NaBH4), quantity of catalyst applied and the effect of microwave irradiation time was evaluated to obtain good results for 4-nitrophenol reduction. The 99.5% 4-nitrophenol reduction was achieved by using 100 mu g of SiO2/Fe3O4 nanocatalyst in a short reaction time. Furthermore, the 4-nitrophenol reduction process utilizing SiO2/Fe3O4 nanostructures as catalyst was very economical and efficient in term of ease of synthesis, low raw materials expenditure and fast recovery/separation of the catalyst using external magnetic field. Besides these characteristics the SiO2/Fe3O4 nanocatalyst is environment-friendly and bio compatible due to its extremely low toxicity. Based on the above characteristics, the SiO2/Fe3O4 nanocatalyst can find some potential applications as heterogeneous catalyst in environmentally and industrially important reactions.