A mixture of graphene oxide (GO) and TiO2 nanocomposites was reduced photocatalytically by UV-irradiation and applied as interfacial layer between a fluorine doped tin oxide (FTO) layer and a nanocrystalline TiO2 film. Impedance spectra implied a decreased back-transport reaction of electrons. The graphene-TiO2 interfacial layer effectively reduced the contact between I-3(-) ions in the electrolyte and FTO layer, which inhibited back-transport reaction. The introduction of graphene-TiO2 increased V-oc by 54 mV and the photoconversion efficiency was improved from 4.89% to 5.26%. (C) 2009 Published by Elsevier B.V.