Gold nanoparticle modified magnetic fibrous silica microspheres as a highly efficient and recyclable catalyst for the reduction of 4-nitrophenol

Recently, catalysts with easily accessible active sites and high efficiency and recyclability have triggered various research interests. In this study, we prepared uniform fibrous silica microspheres with a gamma-Fe2O3 magnetic core (gamma-Fe2O3@SiO2@KCC-1) as the catalyst support. The distance between two fibers was approximately 10-20 nm. Au nanoparticles (NPs) were highly dispersed on the silica fibers without aggregation to form the nanocatalyst Au/gamma-Fe2O3@SiO2@KCC-1. The catalytic activity of Au/gamma-Fe2O3@SiO2@KCC-1 for the reduction of 4-nitrophenol (4-NP) with NaBH4 was measured by UV-vis spectroscopy. Au/gamma-Fe2O3@SiO2@KCC-1 exhibited better catalytic activity toward the reduction of 4-NP compared with other reported Au NP-based catalysts. The high catalytic activity was mainly attributed to the easy accessibility of the Au NPs of the prepared nanocatalyst. In addition, Au/gamma-Fe2O3@SiO2@KCC-1 could be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after six runs. The unique properties provided an ideal platform to study various noble metal/gamma-Fe2O3@SiO2@KCC-1 nanocatalysts that can be potentially applied in a wide variety of fields such as catalysis and green chemistry.