Fig. 2

Structure and composition characterization of rGO@Fe3O4. (a, b) SEM with EDS mapping pictures of rGO@Fe₃O₄ microspheres: C, Fe, and O elements; (c) XRD patterns of rGO-SiO₂, rGO and rGO@Fe₃O₄ microspheres; (d, e) SEAD images of rGO@Fe₃O₄ microspheres; (f) TG curves of rGO@Fe₃O₄ microspheres; (g, h) XPS spectra of rGO@Fe₃O₄ microspheres; (i) Magnetic hysteresis loops of the Fe₃O₄ and rGO@Fe₃O₄ microspheres (inset of top shows coercive field values (Hc) of samples, and inset of the bottom shows their suspensions before and after magnetic separation by an external magnet)