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 degrees C under oxidizing (O-2), inert (N-2) and (Ar) and reducing (N-2/H-2) 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 angstrom) with high crystallinity. HRTEM images show the multi-layers TiO2-G sheets with thicknesses similar to 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 N-2/H-2, the produced TiO2-G shows a higher photocatalytic activity than those treated in N-2 and O-2. 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. (C) 2012 Elsevier B.V. All rights reserved.