We demonstrated for the first time by large-scale ab initio calculations that a graphene/titania interface in the ground electronic state forms a charge transfer complex due to the large difference of work functions between graphene and titania, leading to substantial hole doping in graphene. Interestingly, electrons in the upper valance band can be directly excited from graphene to the conduction band, i.e. the 3d orbitals of titania, under visible light irradiation. This should yield well-separated electron-hole pairs, with potentially high photo-catalytic or photo-voltaic performance in hybrid graphene and titania nanocomposites. Experimental wavelength-dependent photocurrent generation of graphene-titania photoanode demonstrated noticeable visible light response evidently verify our ab initio prediction.
Available at: http://works.bepress.com/yunhau_ng/31/