Detailed photocatalytic study of alkaline titanates and its application for the degradation of methylene blue (MB) under solar irradiation

Alkaline titanate nanomaterials with mixed anatase and titanate phases had been produced via hydrothermal synthesis. The XRD patterns of the samples indicated the presence of the anatase peak at 2 theta = similar to 25 degrees except for Na-TiO(2)200 degrees C/12 h. The Dr-UV/Ws analysis indicated that the band gap energy for Li-TiO(2)200 degrees C/12 h, Na-TiO(2)200 degrees C/12 h, K-TiO(2)200 degrees C/12 and Cs-TiO(2)200 degrees C/12 h to be 3.12, 3.05, 3.07 and 3.17 eV respectively. The alkaline titanate samples were shown to possess lower recombination rate of the photogenerated charge carriers (e(-)/h(+)) in comparison to that of pure anatase TiO2, except for K-TiO(2)200 degrees C/12 h. The surface area of the samples was calculated to be 32.0, 120.0, 155.0 and 24.3 m(2) g(-1) for Li-TiO(2)200 degrees C/12 h, Na-TiO(2)200 degrees C/12 h, K-TiO(2)200 degrees C/12 h and CsTiO(2)200 degrees C/12 h respectively. Li-TiO(2)200 degrees C/12 h exhibited enhanced photocatalytic efficiency in the photodegradation of MB compared to Degussa P25 and anatase TiO2. In addition, NaTiO(2)200 degrees C/12 h, K-TiO(2)200 degrees C/12 h and Cs-TiO(2)200 degrees C/12 h also showed excellent adsorptive properties.