Synthesis of Fe-doped TiO2 with improved photocatalytic properties under Vis-L irradiation

Authors

• Imane Ellouzi * ¹
• Boutaina Regraguy ¹
• Souad El Hajjaji ¹
• Mourad Harir ²
• Philippe Schmitt-Kopplin ³
• Hinda Lachheb ²
• Larbi Laânab ³

1. Laboratory of Spectroscopy, Molecular Modeling, Materials, Nanomaterials, Water and Environment, CERNE2D, Faculty of Sciences, Mohammed V University, in Rabat Av. Ibn Batouta, BP 1014 Rabat, Morocco
2. Unité de Recherche Catalyse et Matériaux pour l’Environnement et les procédés (URCMEP), Faculté des sciences de GABES/Université de Gabes. Campus Universitaire.Cité Erriadh 6072 Gabes, Tunisia
3. Laboratory of Conception and Systems, Faculty of Sciences, Av. Ibn Batouta, BP 1014 Rabat, Morocco

Abstract

Fe-doped TiO₂ nanoparticles were successfully synthesized by the coprecipitation method. TiO₂ was doped with a different molar ratio of iron amounts, namely 0.1% and 0.2%. An undoped TiO₂ was also prepared for comparison. X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-visible diffuse reflectance spectroscopy techniques were used to characterize the as-synthesized nanoparticles. The XRD spectra revealed that the photocatalysts were mostly in a well-crystallized anatase phase. Optical properties of the powders shifted from UV to the beginning of the visible light (Vis-L) region. Absorption edge wavelengths between 392 and 380 nm were obtained for the Fe-doped TiO₂ and TiO₂-P25, corresponding to band gap energies between 3.17 and 3.26 eV. TEM images showed homogeneity with a certain degree of agglomeration for all the samples. The photocatalytic efficiency of the as-synthesized Fe-doped TiO₂ nanoparticles was performed using azo dye methyl orange (MO) in an aqueous solution under Vis-L irradiation. The photocatalytic results showed that Fe-doped TiO₂ nanoparticles effectively degrade MO under Vis-L excitation and follow pseudo-first order kinetics. Besides, kinetic comparison showed that pure TiO₂ is less efficient than 0.1% and 0.2% Fe-doped TiO₂ because they exhibit unequaled efficiency. Moreover, the photocatalyst at 0.2% Fe-doped TiO₂ molar ratio revealed the highest photocatalytic efficiency, which was 4.2 times higher compared to pure TiO₂. Different amounts of Fe induced different increases in the apparent first-order rate constant of the photocatalytic process.

Highlights

• Synthesis of Fe/TiO₂ via coprecipitation method.
• Fe-TiO₂ materials observed greater performance than that of pure Degussa P25.
• The photo-activity of iron-doped TiO₂ under visible light irradiation was evaluated.
• The pseudo-first-order rate kinetics indicates a rate-limiting step involving a chemical reaction.

Graphical Abstract

Keywords

• Titanium dioxide
• Coprecipitation
• Photocatalytic Degradation
• Iron
• MO.