Tuning the phase composition of 1D TiO₂ by Fe/Sn co-doping strategy for enhanced visible-light-driven photocatalytic and photoelectrochemical performances

The development of multi-functional visible-responsive TiO₂-based photocatalysts remains a long-term goal as a promising strategy for dealing with the issue of antibiotic-residues in natural streams. Herein, for the first time, photodecomposition of a typical antibiotic, tetracycline (TC), over Fe and Sn co-doped-TiO₂ nanofibers (Fe/Sn–TiO₂ NFs) was evaluated under simulated visible-irradiation. A facile PVP-assisted electrospinning method was utilized to fabricate a series of TiO₂ NF-based photocatalysts. Notably, compared with the pristine and single doped-TiO₂ samples, Fe/Sn–TiO₂ showed supreme photocatalytic efficiency and cycling photostability, capable of eliminating over 92% of the TC within 60 min after 5 cycles. Benefiting from the shortened band gap to harvest visible-light, the co-doped sample exhibited a dominant anatase phase, which could enhance photocatalytic activity. In addition, a kinetic analysis was performed to verify that the apparent photodegradation rate followed the Langmuir–Hinshelwood kinetic model. Moreover, the favored separation and transmission of charge-carriers in the Fe/Sn–TiO₂ were studied using photoluminescence and photoelectrochemical analyses. The Fe/Sn–TiO₂ was able to degrade 81.85% and 60.59% of TC in tap and river waters, respectively, after 60 min illumination. Additionally, electron paramagnetic resonance and radical scavenging experiments were carried out to demonstrate that ^●OH and ^●O₂⁻ radicals were involved in the degradation of TC over Fe/Sn–TiO₂. Degradation pathways of TC were investigated using liquid chromatography-mass spectrometry and the enhanced photodegradation mechanism was discussed in detail. Overall, the present work could provide reliable guidelines for the design and synthesis of boosted one-dimensional photocatalysts with potential applications in drug decontamination.