Photodegradation of 4-SPPN dye catalyzed by Ni(II)-substituted Bi2VO5.5 system under visible light irradiation: Influence of phase stability and perovskite vanadate-oxygen vacancies of photocatalyst

The BINIVOX.x system, (Bi2NixV1-xO5.5-(3x/2))-V-(II), with a layered Aurivillius-type structure was developed as a novel photocatalyst for degradation of organic dyes. A series of BINIVOX.x photocatalyst in the composition range 0 <= x <= 0.20 were successfully synthesized by the standard solid-state reaction and characterized using X-ray powder diffraction (XRPD), differential thermal analysis (DTA), UV-vis diffuse reflectance spectroscopy (UV-vis/DRS) and BET surface area. The photocatalytic activities of prepared catalysts were investigated for the first time through the degradation of a new azo dye, 4-SPPN in aqueous solution under visible light irradiation. Adsorption efficiency and photocatalytic activity of BINIVOX.x catalysts were correlated well with the variation in phase crystal structures stabilized at room temperature as a function of composition. The best photocatalytic performance exhibited by gamma'-stabilized BINIVOX phases of the tetragonal symmetry (space group 14/m mm) can be attributed to their higher specific surface area, narrower band-gap energy and higher oxygen vacancy concentration in the perovskite vanadate layers. In addition, the possible photocatalytic degradation mechanism of 4-SPPN dye was proposed under visible light irradiation. (C) 2013 Elsevier B.V. All rights reserved.