Fe₃O₄-TiO₂ Thin Films in Solar Photocatalytic Processes

The optical properties of 5wt% Fe₃O₄-TiO₂ thin films were evaluated in detail with the aim of proposing a mechanism for solar photocatalytic processes and highlighting the advantages over the use of bare TiO₂. The results showed that the incorporation of 5wt% Fe₃O₄ enhanced the optical properties by a redshift to a wavelength in the visible range, reducing the anatase/rutile band gap energy from 3.2 eV to 2.8 eV. Photoluminescence studies reveal a superior separation efficiency of photoexcited electron-hole pairs when Fe₃O₄ nanoparticles (NPs) are present in the photocatalyst. X-ray photoelectron spectroscopy spectra confirm the presence of Fe₃O₄ and existence of a chemical bonding between TiO₂ and Fe₃O₄ NPs. Moreover, in this study, a mechanism of solar photocatalytic processes involving Fe₃O₄-TiO₂ thin films is proposed and it is supported by experimental results. Finally, solar photocatalytic experiments were carried out, indicating that the effectiveness for the removal of the selected pharmaceutical is considerably improved when the composite material is used as catalyst. Furthermore, it was demonstrated that the photocatalytic activity of the prepared Fe₃O₄-TiO₂ thin films depends on their thickness, achieving the highest pharmaceutical removal yields using the 2 µm thick sample. The stability and reusability of the catalyst was confirmed studying the photocatalytic activity over three cycles.