Biogenic Synthesis of Magnetic Palladium Nanoparticles Decorated Over Reduced Graphene Oxide Using Piper Betle Petiole Extract (Pd-rGO@Fe3O4 NPs) as Heterogeneous Hybrid Nanocatalyst for Applications in Suzuki-Miyaura Coupling Reactions of Biphenyl Compounds

Biogenic synthesis of magnetic palladium decorated over reduced graphene oxide (Pd-rGO@Fe3O4) nanoparticles (NPs) were carried out using Piper betle petiole extract. The reduction of palladium (+ 2) to palladium (0) oxidation state, graphene oxide to reduced graphene oxide carried out by the phytochemicals present in the petiole extract which aids in reduction as well as stabilizing the formed (Pd-rGO@Fe3O4) nanoparticles. Liquid chromatography with mass spectrum (LC-MS) as detector was used to identify the major phytochemicals present in the Piper betle petiole extract. The reduced graphene oxide creates a mesoporous structure for the palladium metal to deposit along with the magnetite which assist in easy recovery of the formed nanoparticles from the reaction course. The synthesized Pd-rGO@Fe3O4 NPs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), and Ultraviolet-visible spectroscopy (UV-vis). Thermal stability of the Pd-rGO@Fe3O4 NPs were carried out using Thermo Gravimetric Analysis (TGA). The synthesized Pd-rGO@Fe3O4 NPs used as hybrid nanocatalyst in Suzuki-Miyaura coupling reaction of biphenyl compounds. The synthesized biphenyl compounds were characterized by Proton Nuclear Magnetic Resonance Spectroscopy (H-1 NMR). The heterogeneous hybrid nanocatalyst Pd-rGO@Fe3O4 NPs recovered, isolated using external magnet and was successfully used for three cycles in C-C coupling reaction without any significant loss in catalytic activity. [GRAPHICS] .