▎ 摘　　要

We have synthesized cobalt nanoparticles-reduced graphene oxide (Co-RGO) nanocomposites. The Co NPs achieve shape variation in different nanocomposites due to the strategic use of variety in the preparation techniques. The transmission electron microscope image of composites confirms the decoration of different shapes of Co NPs on RGO sheets. The magnetic study with the variation of temperature indicates a change in the form of hysteresis loops. This is due to the transition from ferromagnetic to superparamagnetic behavior. We found that cubic-shaped Co NPs while decorating RGO show the highest values for some critical magnetic parameters. Coercivity, magnetic moment, and squareness ratio are these parameters. Besides, the nanocomposite-impregnated aqueous sols are found to be quite stable and could be a potential candidate for inkjet printing and ferrofluid as the squareness ratio (M-r/M-S) is very small.