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

Abstract

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) (3.54Å) with high crystallinity. HRTEM images show the multi-layers TiO2–G sheets with thicknesses ∼2.4nm. 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.