Commercial Degussa P25 (Degussa Company, Germany) is a
well-known efficient TiO2 photocatalyst; therefore, the preparation
of a P25-based composite with intact intrinsic properties is
of great importance. Recently, Zhang et al. [22] applied commercial
P25 and graphene oxide as TiO2 precursor and carbonaceous
source; subsequently, they prepared P25-solvothermally reduced
graphene composite by hydrothermal treatment with ca. 1 wt%
of carbon content. The photocatalytic activities of pure P25,
P25–graphene and P25–carbon nanotube composites were compared
through the photodegradation of methylene blue upon UV
and visible lights. However, to our knowledge, the simple preparation
of P25/graphene oxide composite as the photocatalyst has
not been reported yet. It is predicted to be more advantageous to
the adsorbability and corresponding photoactivity when preparing
a TiO2/graphene oxide composite system due to the presence
of abundant functional groups at the edge or on the surface of
graphene oxide layers compared to those of graphene sheets. Furthermore,
the one-step colloidal blending is an environmentally
friendly and simple method that preserves the TiO2 characteristics
and combines the outstanding advantages of graphene oxide
sheets, including excellent electronic conductivity and large surface
area.