Influence of iron-based salts and silica nanoparticles on the phase transition, morphology, and photocatalytic activity of electrospun TiO2 nanofibers

Electrospun TiO 2 nanofibers (NFs) were modified using different dopant chemistries to investigate the influence of iron-based salts and silica nanoparticles on phase composition, microstructure, and photocatalytic performance. Pristine TiO 2 NFs calcined at 600 °C exhibited a pure anatase phase, whereas doping with ferrous acetate, ferrocene, and SiO 2 nanoparticles induced distinct structural transformations. X-ray diffraction analysis revealed mixed anatase–rutile phases in all doped samples, with a markedly higher rutile-to-anatase ratio for FeAC-doped TiO 2 compared to ferrocene-doped nanofibers, while SiO 2 -doped TiO 2 retained an anatase-dominant structure. Weak diffraction peaks corresponding to Fe 2 O 3 and SiO 2 confirmed successful dopant incorporation at low loadings without disrupting the TiO 2 crystalline framework. Electron microscopy analyses demonstrated that dopant chemistry strongly affected nanofiber morphology, crystallinity, and lattice structure. Ferrocene and SiO 2 doping produced sharper diffraction features, higher crystallinity, and increased lattice spacing (up to ∼0.29–0.30 nm) compared to pristine and FeAC-doped TiO 2 , as confirmed by HRTEM and SAED analyses. Photocatalytic performance was evaluated using methylene blue degradation and real sewage wastewater treatment. Among the investigated formulations, ferrocene-doped TiO 2 nanofibers exhibited the best overall photocatalytic performance under both UV and visible light irradiation. In real sewage wastewater treatment, ferrocene-doped TiO 2 reduced the COD from 220 mg.L⁻¹ to ∼16 mg.L⁻¹ under visible light and to ∼34 mg.L⁻¹ under UV irradiation, while SiO 2 -doped TiO 2 reduced the COD to ∼24 and ∼39 mg.L⁻¹ , respectively. The enhanced activity is associated with favorable phase composition, improved crystallinity, and dopant-induced interfacial structural modifications. These results demonstrate that dopant type and incorporation route play a key role in tailoring the structure and photocatalytic performance of TiO 2 nanofibers.