Fluorine‐doped TiO₂ nanoparticles sensitized by tetra(4‐carboxyphenyl)porphyrin and zinc tetra(4‐carboxyphenyl)porphyrin: Preparation, characterization, and evaluation of photocatalytic activity

In this study, TiO 2 nanoparticles have been doped with fluorine (F‐TiO 2 ) and consequently sensitized with tetra(4‐carboxyphenyl)porphyrin (TCPP/F‐TiO 2 ) or zinc tetra(4‐carboxyphenyl)porphyrin (ZnTCPP/F‐TiO 2 ) to extend their light absorption into the visible region. The prepared photocatalysts were characterized by SEM, XRD, FTIR, and UV‐Vis assays. F‐TiO 2 nanoparticles were completely in anatase phase with particle size range of 50−200 nm. Fluorine‐doping of the TiO 2 nanoparticles led to a red shift in their absorption spectrum, while did not significantly changed their band gap (from 2.9 to 2.8 eV). ZnTCPP/F‐TiO 2 and particularly TCPP/F‐TiO 2 nanoparticles displayed improved visible light absorbency with decreased band gap values (1.5 and 2.4 eV, respectively). The photocatalytic activity of the nanoparticles has been studied through degradation of Rhodamine B in aqueous media under UV and visible light irradiation. The prepared photocatalysts showed lower activity than Degussa P‐25 under UV light irradiation. However, under visible light irradiation, F‐TiO 2 nanoparticles better photocatalyzed the RhB degradation than Degussa P‐25. Meanwhile, ZnTCPP/F‐TiO 2 and mainly TCPP/F‐TiO 2 nanoparticles were completely photoactive under visible light irradiation.