Photoelectrochehical studies on the mixed oxides,SrTiO₃,Sr₂TiO₄ and Sr₃Ti₂O₇

PEC studies on Sr₂TiO₄ and Sr₃Ti₂O₇, two members of the homologous series, Sr_n+1Ti_nO_3n+1, which are chemically related to but structurally different from SrTiO₃ ana contain TiO₆ photoactive centres, have been carried out and the results compared to the behaviour of SrTiO₃. Photopotential, photocurrent vs. applied voltage and wavelength data indicate that Sr₂TiO₄, and Sr₃Ti₂O₇ possess large and indirect band gaps (3.25 and 3.22 eV) similar to SrTiO₃ (E_g = 3.20 eV) but have slightly lower flat band potentials than SrTiO₃ and hence need slightly larger bias voltages for operation in the PAE mode. Long term stability studies under illumination indicate that while Sr₃Ti₂O₇ is almost as stable as SrTiO₃, Sr₂TiO₄ shows degradation.