Nanogold-decorated reduced graphene oxide for catalytic hydrogenation of 4-nitrophenol

Abstract

The current work focuses on the efficacious synthesis of Au nanoparticles (NPs) decorated on reduced graphene oxide (RGO) sheets and evaluating and comparing the catalytic efficiency of the latter with graphene oxide (GO) and reduced graphene oxide (RGO) for the hydrogenation of 4-nitrophenol (4-NP). 4-NP is one of the most hazardous and widely investigated nitro compounds. Here, we report a single-step co-reduction approach for synthesizing AuRGO using hydrazine monohydrate as a reducing agent. X-ray diffraction (XRD) patterns of prepared samples confirmed the formation of GO, RGO, and AuRGO. Raman analysis gave insight into the structure and defects of prepared samples. The various oxygen-containing moieties are identified using Fourier transform infrared (FTIR) spectra and confirmed the loss of these functional groups during the reduction of GO into RGO. UV absorption analysis is carried out and is also reinforced by the finite difference time domain (FDTD) simulation studies. X-ray photoelectron spectroscopy (XPS) analysis yielded quantitative information regarding the reduction of GO into RGO and the decoration of zerovalent Au NPs on the RGO surface. Thermogram of the prepared samples manifests the thermal stability of the samples. Field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) images depicted the morphology of GO, RGO, and AuRGO. The catalytic efficiency of AuRGO is tested by reducing 4-nitrophenol (4-NP) in the presence of sodium borohydride. AuRGO has shown enhanced catalytic efficiency compared to GO and RGO.