Imidazolium ionic liquid-modified fibrous silica microspheres loaded with gold nanoparticles and their enhanced catalytic activity and reusability for the reduction of 4-nitrophenol

A new type of catalyst based on the ionic liquid (IL) modified fibrous nano-silica material KCC-1, with a high surface area, as the support and Au nanoparticles (NPs) as the active sites (KCC-1–IL/Au), has been successfully prepared through a facile and environmentally-friendly approach and characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA), elemental analysis and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The synthesized catalyst exhibited high catalytic activity in the reduction of 4-nitrophenol by NaBH4 due to not only the unique dendritic fibrous morphology of the support, which made the active sites accessible, but also the synergistic effect between KCC-1–IL and the small Au NPs. Additionally, KCC-1–IL/Au had good recyclability, mainly attributed to the IL groups, which acted as robust anchors to avoid Au NP leaching from the support. This synthetic method provides a green way to effectively prepare low-cost Au-based catalysts and is promising for the development of other useful materials.