Visible-Light-Driven AO7 Photocatalytic Degradation and Toxicity Removal at Bi-Doped SrTiO 3 .

In this study, Bi-doped SrTiO 3 perovskites (Sr 1-x Bi x TiO 3 , x = 0, 0.03, 0.05, 0.07 and 0.1) were synthesized using the solid-state method, characterized, and tested as photocatalysts in the degradation of the azo dye acid orange 7 (AO7) under visible light. The perovskites were successfully synthesized, and XRD data showed a predominant, well-crystallized phase, belonging to the cubic perovskite symmetry. For the doped samples, a minority phase, identified as bismuth titanate, was detected. All doped samples exhibited improved photocatalytic activity under visible light, on the degradation of AO7 (10 mg L -1 ), when compared with the undoped SrTiO 3 , with an increase in relative Abs 484 nm decay from 3.7% to ≥67.8% after 1 h, for a powder suspension of 0.2 g L -1 . The best photocatalytic activity was exhibited by the Sr 0.95 Bi 0.05 TiO 3 perovskite. Reusability studies showed no significant loss in photocatalytic activity under visible light. The final solutions showed no toxicity towards D. magna , proving the efficiency of Sr 0.95 Bi 0.05 TiO 3 as a visible-light-driven photocatalyst to degrade both the AO7 dye as well as its toxic by-products. A degradation mechanism is proposed.