Green synthesis and characterization of monolayer rGO functionalized with Fe3O4 magnetic nanoparticles for efficient and recyclable catalytic production of benzimidazoles

A green and magnetically recoverable heterogeneous nanocatalyst by anchoring Fe3O4 magnetic nanoparticles (MNPs) onto monolayer reduced graphene oxide (rGO), denoted as rGO@Fe3O4. The Fe3O4 MNPs were found uniformly distributed on the rGO nanosheet, forming a stable and efficient nanoconmposite which was fully characterized through FT-IR, Raman, UV–Vis spectroscopy, XRD, AFM, FESEM, EDX, SEM coupled EDX (SEM mapping), TEM, VSM, ICP, TGA and BET techniques. This catalyst provided a sustainable, recyclable and eco-friendly catalytic platform for the synthesis of 4H-pyrimido [2,1- b] benzimidazoles giving 95–99% yields at lower temperature (45 °C) and shorter reaction time (5–10 min) compared to the previously reported methods.