Properties of materials such as band gap, electron-hole pair lifetime and electron and hole mobility greatly affect the efficiency of solar energy conversion devices [3, 4]. Moreover, redox reactions on the surface of materials take place only if the energy of conduction band minimum lies above and for valence band maximum lies below the redox reaction free energies. Accurate information about the band edge position is the criteria that a material must fulfill to be active photoelectrode or photocatalyst [5].
Photocatalysis via oxide semiconductors has brought up attention of many people due to its high efficiency and wide applications in environmental pollution decomposition [6-8]. Extensive research has been carried out to investigate the photocatalytic properties of oxide semiconductors under visible light irradiation. Such as AgAlO2 [9] (Eg ~ 2.8 eV) decomposes dye alizarin red (AR) photocatalytically and the decomposition rate increases up to 70 % under light irradiation.