Highly efficient and recyclable graphene oxide-magnetite composites for isatin mineralization

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