Methyl Orange Dye degradation of dual doped TiO2 nanoparticles under visible light Irradiation

Abstract

Zirconium (Zr) and phosphorus (P) co-doped TiO₂ nanoparticles were synthesized using a sol-gel technique, to improve the photocatalytic degradation of Methyl Orange dye under visible light. UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to characterise the structural and optical characteristics. TPZr6 (0.25 wt% Zr, 1 wt% P) had the smallest crystallite size (3.06 nm), and XRD verified the anatase phase in all samples. Because there were no notable new chemical bonds found by FTIR, the structure was stable. According to UV–visible spectroscopy, TPZr6 had a smaller band gap (2.01 eV) than undoped TiO₂ (3.2 eV), which allowed for effective absorption of visible light. With a rate constant of 0.0303 min⁻¹, photocatalytic tests showed that TPZr6 outperformed undoped and other doped samples (TPZr1–TPZr5) in achieving 93 % degradation of Methyl Orange in 48 min. The optimised band gap, decreased electron-hole recombination, and large surface area of TPZr6 are responsible for its improved performance. The stability of TPZr6 across five cycles with little loss of efficiency was validated by recycling testing. These results demonstrate that Zr/P co-doped TiO₂, in particular TPZr6, is a very effective photocatalyst for wastewater treatment dye degradation.