▎ 摘　　要

Graphene based magnetic nanoparticles (NPs) have attracted considerable attention in numerous applications owing to their splendid chemical and physical properties. However, the synthesis approaches are often complex and relatively expensive. In the present study, we report the fabrication of magnetic graphene oxide (GO) nanocomposites (denoted as Fe3O4/GO) via an effective electrostatic strategy under ultrasonic waves using the bare Fe3O4 NPs initially synthesized via a co-precipitation method. The Fe3O4 NPs were uniformly covered by the crumpled-like GO matrix, as confirmed by transmission electron microscopy. Their structure and magnetic behaviors were investigated via Fourier transform infrared spectroscopy and vibrating sample magnetometer curves. The appealing dual electro/ magnetorheological performance of the as-prepared Fe3O4/GO dispersed in silicone oil was investigated using a rotational rheometer under applied electric or magnetic fields, respectively. Their dynamic yield stress values were analyzed using a universal equation, and the MR efficiency was observed to be higher than that of the ER.