A facile auto-combustion pathway for creating Mn- and Fe-doped TiO2 nanostructures and their photocatalytic activity

Abstract

Using a combination of two fuels, an auto-combustion method was used to synthesize pure TiO₂ and doped TiO₂ with different concentrations of iron(III) (Fe) and manganese(II) (Mn) (1, 3, 5, and 7 mol%). The as-prepared materials were characterized using different techniques, including thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). The XRD results showed that both pure TiO₂ and all doped TiO₂ samples had the anatase phase, indicating the crystalline nature of all the as-prepared nanomaterials. Crystal violet decolorization under UV irradiation was used to assess the photocatalytic activity of the prepared samples. The findings showed that, compared to other dopant concentrations, TiO₂ with a dopant concentration of 5% Fe and 7% Mn showed the highest degradation rates (95.93% and 96.3%, respectively) at 100 and 70 min, with pseudo-first order rate constants of k = 2.91 × 10⁻² and 4.8 × 10⁻² min⁻¹, respectively. It was found that superoxide radicals and hydroxyl radicals were the main reactive species responsible for dye degradation.