Synthesis and Characterization of Gel-Derived, Highly Al-Doped TiO₂(Al _x Ti_1–x O_2–x/2; x = 0.083, 0.154, 0.2) Nanoparticles: Improving the Photocatalytic Activity

Highly aluminium-doped TiO₂ nanoparticles were synthesized using a sol–gel method. The synthesized nanoparticles were annealed at different temperatures and their properties were characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, XPS, and UV-Vis to determine their composition, crystalline structure, band gap energy and possible use as semiconductors in photocatalytic and photovoltaic applications. The results revealed high internal doping due to the substitution of Ti⁴⁺ ions by Al³⁺ in the TiO₂ lattice. The transformation from anatase to rutile phase occurred at higher temperatures when doping was increased. Furthermore, Raman, FT-IR and XPS showed the formation of oxygen vacancies to conserve the local charge neutrality in the TiO₂ lattice. Thus, applying the synthesized material in photovoltaic and photocatalytic applications could be of interest. A photocatalytic application was developed based on the photodegradation of methylene blue. The aluminium doped samples synthesized in this study showed higher photocatalytic activity than the undoped ones.