Fabrication and photocatalysis of TiO2-graphene sandwich nanosheets with smooth surface and controlled thickness

GO: graphene oxide; TGO: TiO2 Graphene oxide; TG: TiO2-graphene. [Display omitted] •Sandwich nanosheets with graphene sheet in the center and TiO2 on its both facets were fabricated.•The surface of the nanosheets is rather smooth with extremely low roughness.•The thicknesses of nanosheets are controllable and show a linear correlation with the weight ratio of TiO2/GO.•Photocatalytic activity of nanosheets rises first and then falls with thickness increasing. TiO2-graphene sandwich nanosheets (TG) with smooth surface and controlled thickness were prepared by a two-step process. First, TiO2-Graphene oxide (GO) nanosheets (TGO) were prefabricated via the controllable hydrolysis of tetrabutyl titanate in ethanol/water suspension of graphene oxide. The sandwich structure of TGO with smooth surface was confirmed by AFM, XPS and XRD. And the thicknesses of TGO varied from 3.4nm to 36.0nm when the weight ratio of TiO2/GO changed from 1.0 to 20.0. Followed by calcination under Ar at 400°C, the sandwich structures were well preserved and their thicknesses still showed a linear correlation with the weight ratio of TiO2/GO. Meanwhile, the amorphous TiO2 on GO was crystallized into anatase and GO was reduced to graphene. Photocatalytic activity of TG was carried out by the degradation of Rhodamine B. It rose first and then fell with the thickness of TG increasing, and TG with thickness of ∼9nm showed the best of all. Our work not only provides a promising route to fabricate graphene based two-dimensional nanomaterials, but also provides a prerequisite to study the influence of nanosheet thickness on their physical and chemical properties.