▎ 摘　　要

A series of graphene oxide-magnetite (GO-Fe3O4) composites with various GO/Fe3O4 weight ratios (i.e., GO/Fe3O4 = 1/20, 2/20, 3/20 and 4/20) was successfully synthesized via chemical precipitation of Fe3O4 nanoparticles on GO nanosheets. The chemical and physical properties of as-synthesized GO-Fe3O4 composites were characterized by XRD, TEM and FT-IR. Results from XRD and TEM revealed that cubic-phase Fe3O4 nanoparticles were in situ deposited on the surface of GO nanosheets resulting in GO-Fe3O4 composites. The C-O-Fe bridging coordination mode was determined by FT-IR, demonstrating the Fe3O4 nanoparticles were well coupled with GO nanosheets by coordination bond. TEM images revealed that two types of geometrical structures of GO-Fe3O4 composites were formed by loading different amounts of GO. With low GO loadings (i.e., GO/Fe3O4 = 1/20, 2/20 and 3/20), single layer structure GO-Fe3O4 composites were obtained. At a high GO loading (i.e., GO/Fe3O4 = 4/20), stacking structure of GO-Fe3O4 composite was formed. The as-prepared GO-Fe3O4 nanocomposites exhibited an excellent catalytic performance in the degradation of isatin in the presence of H2O2. With GO/Fe3O4 weight ratio of 3/20, GO-Fe3O4 composites showed superior degradation efficiency of isatin, mainly due to the effective functional combination between GO nanosheets and Fe3O4 nanoparticles. (C) 2017 Elsevier B.V. All rights reserved.