TiO2 decoration of graphene layers for highly efficient photocatalyst: Impact of calcination at different gas atmosphere on photocatalytic efficiency

Graphene based two-dimensional carbon nanostructures serve as a support to disperse TiO2 nanoparticles. Here, a facile decoration of graphene oxide (GO) and reduced graphene oxide (G) sheets with TiO2 nanoparticles at different contents (1–10%) has been demonstrated. Then the as-prepared TiO2–GO samples were heat treated at 450 °C under oxidizing (O2), inert (N2) and (Ar) and reducing (N2/H2) conditions to obtain multi-layers TiO2–GO and TiO2–G nanocomposites. The findings indicated that the lattice fringes of TiO2 anatase exhibit the typical distances of (101) (3.54 Å) with high crystallinity. HRTEM images show the multi-layers TiO2–G sheets with thicknesses ∼2.4 nm. The newly prepared multi-layers TiO2–GO and TiO2–G nanocomposites have been compared with a commercial photocatalyst P-25 by the determination of their photocatalytic efficiencies for degradation of methylene blue. It can be observed that when TiO2–GO calcining in N2/H2, the produced TiO2–G shows a higher photocatalytic activity than those treated in N2 and O2. Also, the photocatalytic degradation rates of MB by TiO2–G are faster 6 and 2 times than that by P25 and TiO2–GO respectively, which is due to the better contact between G and TiO2 and the more effective charge transfer from TiO2 to G multi-layers. From the economic point of view, the consumed amount of TiO2–G sheets in photocatalysis process is one fifth of commercial photocatalyst P-25 without loss of photocatalytic performance. Incorporation of TiO2 nanoparticles onto multi-layers graphene sheets provide greater versatility in carrying out photocatalytic processes.

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► A facile decoration of graphene oxide (GO) with TiO2 (1–10%) has been demonstrated.
► HRTEM images show the multi-layers TiO2–GO sheets with thicknesses ∼2.4 nm.
► TiO2–GO calcining in N2/H2, shows a higher photocatalytic activity than those treated in N2 and O2.
► The photoactivity by TiO2–G are faster 6 and 2 times than that by P25 and TiO2–GO respectively.