Assembly of evenly distributed Au nanoparticles on thiolated reduced graphene oxide as an active and robust catalyst for hydrogenation of 4-nitroarenes

Thiol-functionalized reduced graphene oxide (SRG) was prepared by coupling the carboxyl groups on the pre-carboxyl-functionalized graphene oxide (GO) with cysteamines through amide bonds. The as-prepared SRG can function both as a support and reducing agent for the formation of Au/SRG nanohybrids with evenly distributed Au nanoparticles on RGO. The thiol linkage on the RGO can act as anchor for Au nanoparticles and due to the existence of the strong interaction between them, the agglomeration of Au nanoparticles can be significantly impeded. The step-by-step assembly process of the Au/SRG nanohybrid was monitored and the products obtained were characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES), atomic force microscopy (AFM), powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The as-prepared Au/SRG nanohybrid showed superior catalytic performance for the hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). It is expected that the method for the preparation of the Au/SRG nanohybrids can also be applied to the preparations of other RGO-based nanohybrid materials which may find a variety of interesting applications.