Degradation of 4-Tert-Butylphenol in Water Using Mono-Doped (M1: Mo, W) and Co-Doped (M2-M1: Cu, Co, Zn) Titania Catalysts

Mono-doped (Mo-TiO 2 and W-TiO 2) and co-doped TiO 2 (Co-Mo-TiO 2, Co-W-TiO 2, Cu-Mo-TiO 2, Cu-W-TiO 2, Zn-Mo-TiO 2, and Zn-W-TiO 2) catalysts were synthesized by simple impregnation methods and tested for the photocatalytic degradation of 4-tert-butylphenol in water under UV (365 nm) light irradiation. The catalysts were characterized with various analytical methods. X-ray diffraction (XRD), Raman, Diffuse reflectance (DR) spectroscopies, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Energy dispersive spectroscopy (EDS) were applied to investigate the structure, optical properties, morphology, and elemental composition of the prepared catalysts. The XRD patterns revealed the presence of peaks corresponding to the WO 3 in W-TiO 2, Co-W-TiO 2, Cu-W-TiO 2, and Zn-W-TiO 2. The co-doping of Cu and Mo to the TiO 2 lattice was evidenced by the shift of XRD planes towards higher 2θ values, confirming the lattice distortion. Elemental mapping images confirmed the successful impregnation and uniform distribution of metal particles on the TiO 2 surface. Compared to undoped TiO 2, Mo-TiO 2 and W-TiO 2 exhibited a lower energy gap. Further incorporation of Mo-TiO 2 with Co or Cu introduced slight changes in energy gap and light absorption characteristics, particularly visible light absorption. In addition, photoluminescence (PL) showed that Cu-Mo-TiO 2 has a weaker PL intensity than undoped TiO 2. Thus, Cu-Mo-TiO 2 showed better catalytic activity than pure TiO 2, achieving complete degradation of 4-tert-butylphenol under UV light irradiation after 60 min. The application of Cu-Mo-TiO 2 under solar light conditions was also tested, and 70% of 4-tert-butylphenol degradation was achieved within 150 min.