Polymorphic transformations and optical properties of graphene-based Ag-doped titania nanostructures.

TiO2 is the most studied semiconductor material for photovoltaics and photocatalyst applications, but due to a very large electron hole recombination process it is difficult to use it as a photovoltaics material. In this context graphene-decorated Ag-doped TiO2 nanostructures have been synthesized by a simple, cost effective chemical method. In this paper, we have studied the structural transformations and electronic band structure of Ag-doped TiO2 due to the incorporation of graphene oxide. Pure rutile and anatase-rutile mixed phases of TiO2 nanoparticles were obtained by Ag doping and annealing at 400 °C. A large red shift was observed in most of the graphene-decorated, doped TiO2 hybrid nanostructures, which is because of the electron transfer between the conduction bands of the doped TiO2 and the multilayer graphene. The Ag-doped TiO2 nanoparticles appear in the shape of a bunch of bananas (or rice-like) because of the jumbled collection of particles, which remain unaltered even after graphene decoration. The strong electrical coupling of Ag-doped TiO2 with reduced graphene oxide produces an advanced hybrid material useful for superior photovoltaics, photocatalytic activity and other applications.