Exfoliation of graphite into graphene in aqueous solution: an application as graphene/TiO2 nanocomposite to improve visible light photocatalytic activity

The aim of this study was the preparation of a graphene/TiO2 heterogeneous catalyst supported on polypropylene for visible light photocatalysis. Aqueous graphene dispersions were prepared by liquid-phase exfoliation of graphite in the presence of a non-ionic surfactant, Triton X-100. The obtained graphene dispersion was characterized by X-ray diffraction, dynamic light scattering and UV-Visible spectroscopy and was subsequently used for the preparation of graphene/TiO2 photocatalyst. As-prepared photocatalysts were tested for the photocatalytic degradation of a refractory dye, Alizarin Red S, in water solutions as target pollutant. Graphene/TiO2 nanocomposites showed higher adsorption of Alizarin Red S on the catalyst surface and higher photocatalytic activity for its degradation under visible light irradiation, in respect to those obtained with pure TiO2.