Dynamically driven perovskite La-Fe-modified SrTiO₃ nanocubes and their improved photoresponsive activity under...

Visible-light active La-Fe-SrTiO₃ (La_0.01Sr_0.99Fe_0.01Ti_0.99O₃) photocatalysts were synthesized via a dynamic hydrothermal route under different NaOH concentrations (2, 3, 4, 5, and 6 M). The results showed that altering NaOH concentrations changed the physicochemical characteristics of the materials. Namely, the decrease in particle size was observed when the NaOH levels were increased. The specific surface area of the photocatalysts changed with an increased concentration of NaOH, and the maximum value was 17.10 m²/g in 5 M of NaOH. The crystal structure of all prepared samples remained unaffected when altered the NaOH concentration or when incorporated La and Fe in the lattice of SrTiO₃. Namely, all samples synthesized under various NaOH concentrations crystallized and maintained in the standard cubic perovskite structure of SrTiO₃. The increased NaOH concentration slightly altered the absorption wavelength towards a longer wavelength region. The La atom, replacing some Sr²⁺ in the structure of modified SrTiO₃, was confirmed to be in the La³⁺ valence state. Simultaneously, Fe atoms demonstrating oxidation states of Fe³⁺ can also be incorporated into the SrTiO₃ network. The photocatalytic degradation of ciprofloxacin antibiotic revealed that the highest performance was approximately 75% within 9 h over the La_0.01Sr_0.99Fe_0.01Ti_0.99O₃ sample prepared at 5 M of NaOH via the dynamic hydrothermal process. Meanwhile, this photocatalyst also displayed greater activity than the pristine SrTiO₃, the single-doped samples (SrFe_0.01Ti_0.99O₃ and La_0.01Sr_0.99TiO₃), and the La_0.01Sr_0.99Fe_0.01Ti_0.99O₃ sample prepared through a static hydrothermal technique under the same synthesis condition.