Perovskite type oxides, sodium bismuth titanate (Na 0.5 Bi 0.5 TiO 3 ), and Ag + , Cu 2+ , and Sn 2+ doped Na 0.5 Bi 0.5 TiO 3 were prepared by pechini and ion exchange methods, respectively. Photocatalytic activities of these catalysts were tested by decomposition of methylene blue (MB) under visible light irradiation. Results showed that the photocatalytic activity of metal ion doped Na 0.5 Bi 0.5 TiO 3 was higher than undoped Na 0.5 Bi 0.5 TiO 3 . Relatively high photocatalytic performance of Ag + -doped Na 0.5 Bi 0.5 TiO 3 is mainly ascribed to the * Dr. M. Vithal 529 efficient separation of electron-hole (e -, h + ) pairs, lower bandgap energy and the creation of active hydroxyl radicals ( • OH). Further, the Ag + -doped Na 0.5 Bi 0.5 TiO 3 catalyst showed good reusability up to four cycles. A possible mechanism for the enhanced photocatalytic performance was proposed. The synthesized photocatalysts were characterized by XRD, SEM, EDS, XPS, FT-IR, and UV/Vis DRS techniques.

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The present work deals with the synthesis, characterization, and photocatalytic studies of layered perovskites belonging to Aurivillius family. Layered perovskites of various chemical compositions, BiREWO 6 (RE ¼ La, Pr, Gd, and Dy), were synthesized by an ethylene glycol eassisted solegel method. These materials were characterized by X-ray diffraction, scanning electron microscopyeenergy dispersive spectroscopy (EDS), Fourier transform infrared, Raman, and ultravioletevisible diffuse reflectance techniques. The composition of all these materials was obtained from EDS. The unit cell lattice parameters were attained from Rietveld refinement program, Fullprof.2k, by refining the d-lines of BiREWO 6 . The band gap energy of these samples was obtained from the KubelkaeMunk plot. The photocatalytic activity of all the samples was evaluated by photodegradation of methylene blue. The mechanistic degradation pathway of methylene blue was studied using radical quenchers.

Phosphates as multifunctional materials were of vital importance in the environmental and energy fields. In the present work, a new cyclophosphate, potassium manganese phosphate (KMnP O ) (hereafter KMPO), was prepared by solid state method. Cations (Ag and Cu ) and anion (N ) were substituted into KMPO lattice via ion-exchange and solid state methods, respectively. The as-prepared materials were characterized by powder X-ray diffraction, SEM-EDS and UV-visible diffuse reflectance spectra. Rietveld refinement was carried out for parent material. All the prepared materials were found to crystallize in the hexagonal lattice and isomorphous with KCoP O . The nitrogen content in N -substituted KMPO was estimated by EDS and O-N-H analysis. The bandgap energy of the cation- and anion-substituted samples was lower compared to that of pristine KMPO. Gouy method was employed to determine the magnetic susceptibility of KMPO. The photoluminescence property of Mn in all the samples was studied, and the color coordinates were calculated using CIE 1931 chromaticity. The photocatalytic activity of visible light active material, N -substituted KMPO, was examined against the degradation of methylene blue and methyl violet at ambient conditions.