Efficient reduction of graphene oxide to graphene nanosheets using a silica-based ionic liquid: synthesis, characterization and catalytic properties of IMD-Si/FeCl4−@GNS

Abstract

The aim of the present protocol is to develop a facile route for the synthesis of novel ionic liquid (IL)-functionalized graphene nano sheets (IMD-Si/FeCl₄⁻@GNS). An imidazolium IL with tetrachloroferrate as an anion (IMD-Si/FeCl₄⁻) was used to reduce graphene oxide. IMD-Si/FeCl₄⁻@GNS were well characterized using various techniques such as Fourier transform infrared (FTIR), Raman, ultraviolet-visible diffuse reflectance spectroscopy (UV-VIS DRS), scanning electron microscopy/energy dispersive X-ray (SEM/EDX), elemental mapping, transmission electron microscopy (TEM), powder X-ray diffraction (XRD), thermal gravimetry (TG), electron paramagnetic resonance (EPR), and X-ray photoelectron spectroscopy (XPS) analyses. The IL-functionalized material was investigated for its catalytic properties and found to be an efficient catalyst for the synthesis of (E)-selective substituted thiosemicarbazone derivatives. The (E)-selectivity was confirmed using DFT calculations which showed that the (E)-isomer was stabilized by 4.90 kcal mol⁻¹ more than the (Z)-isomer. The catalyst maintained its catalytic activity for six successive runs.