Enhanced photocatalytic activity of graphene oxide/titania nanosheets composites for methylene blue degradation

In the present work, we report enhanced photocatalytic degradation of methylene blue dye in aqueous solution by using ultra-thin anatase TiO2 nanosheets (NSs) combined with graphene oxide (GO) as a photocatalyst. The two-dimensional ultra-thin anatase TiO2 NSs are fabricated via chemical exfoliation. By completely delaminating a lepidocrocite-type layered protonic titanate HxTi2−x/4□x/4O4·H2O (x=0.7, □: vacancy) into individual layers through ion exchange with tetrabutylammonium (TBA+) cations, well-dispersed ultra-thin colloidal Ti0.91O2 NSs with a lateral size up to a few micrometers are obtained. Subsequent acid treatment induces colloidal Ti0.91O2 to reassemble and precipitate into a gelation form, followed by thermal annealing to convert the Ti0.91O2 gelation into anatase TiO2 nanosheets as photocatalyst for methylene blue degradation. TiO2 NSs show a high photocatalytic degradation efficiency of 53.2% due to the ultra-thin thickness for facile electron transfering and large surface area for methylene blue absorption. Moreover, photocatalytic effect can be further improved by simply adding GO suspension to achieve colloidal self-assembly of GO and TiO2 NSs. An optimal GO content of 3 wt% further increases the photocatalytic degradation efficiency to 91.2% due to faster electron–hole seperation and improved surface area provided by GO. This work provides a simple but effective approach by combing graphene oxide with TiO2 nanosheets synthesized via the exfoliation method for methylene blue degradation.