Enhanced visible light photocatalytic activities of 3D Fe3O4@SiO2@ZnO/ ZnS nanocomposites by assembling 2D graphene sheets

In this work, Fe3O4@SiO2@ZnO/ZnS-graphene nanocomposites were prepared via a convenient synthetic route. The SEM and TEM analysis confirmed the successful assembly of 3D Fe3O4@SiO2@ZnO/ZnS nanocomposites and 2D graphene sheets. In comparison with FSZZ, FSZZ-GR exhibited the lower bandgap value with a significant redshift and enhanced visible light absorption. The effect of the assembling amount of graphene on the photocatalytic activity was systematically investigated. In the as-prepared photocatalysts, the FSZZ-GR5% sample showed the remarkably enhanced photocatalytic activity towards the degradation of TC under visible light irradiation, benefiting from the band structure of ZnO/ZnS and the incorporation of a proper number of graphene, which can facilitate the efficient separation and migration of photogenerated e-h pairs. The photocatalytic reaction occurred both on the surface of the type-II ZnO/ZnS core/shell heterostructure and the graphene sheets. As a result, the FSZZ-GR5% exhibited the synergistic enhanced photocatalytic performance; the possible photocatalytic mechanism was discussed in detail.