Investigation on structural and photocatalytic properties of complex perovskites Sr4Sr2B ' O-2(11)(B ' = Ta, Nb)

Photocatalytic activity of complex perovskites Sr4Sr2B ' O-2(11)(B = Nb, Ta) has been investigated in this study. Phase pure complex perovskites are synthesised by solid-state reaction method. Structural characterizations reveal that the synthesized perovskite oxides have cubic crystal structure with different cell dimensions. The bandgaps of synthesised Sr-4(Sr2Ta2)O-11(SST) and Sr-4(Sr2Nb2)O-11(SSN) are found to be 4.64 and 4.08 eV respectively. The dye adsorption activities of SST and SSN are studied using Congo red dye under UV lamp and Xenon lamp radiation. The presence of Ta and Nb at octahedral site of the perovskite structure exhibit varying impact on dye degradation process. SST exhibited the highest percentage of dye decolorization (98.2%) under Xenon lamp radiation. Though both SST and SSN have oxygen vacancies both on the surface and bulk, better photocatalytic activity of SST can be attributed to its higher surface area, higher valence band potential and lower recombination rate due to larger band gap favorable for photo-oxidation.