Enhanced Photocatalytic Degradation of Methylene Blue Using La3+ and Mo6+ Co-Doped TiO ₂ Nanotubes

La[Formula: see text] single-doped and La[Formula: see text]–Mo[Formula: see text] co-doped TiO 2 nanotubes were synthesized via anodic oxidation combined with a two-step electrochemical process. Their crystalline structure, microstructure and light absorption properties were characterized using XRD, SEM and UV-Vis spectroscopy, followed by methylene blue photocatalytic degradation experiments. The results indicate that both La[Formula: see text] single-doping and La[Formula: see text]–Mo[Formula: see text] co-doping can suppress the transformation of the anatase phase to the rutile phase and inhibit grain growth. The diameters of both types of nanotubes range between 60[Formula: see text]nm and 80[Formula: see text]nm, with La and Mo uniformly distributed throughout the nanotubes. Both La[Formula: see text] single-doped and La[Formula: see text]–Mo[Formula: see text] co-doped induced red shifts in the TiO 2 light absorption peaks. The most pronounced red shift in the light absorption band edges occurred at a La[Formula: see text]–Mo[Formula: see text] ratio of 3:7, reducing the bandgap width to its minimum value of 2.99 eV. Both La[Formula: see text] single-doped and La[Formula: see text]–Mo[Formula: see text] co-doped TiO 2 exhibited first-order photocatalytic degradation of methylene blue. As the La[Formula: see text] single-doped concentration increased or the La[Formula: see text]–Mo[Formula: see text] co-doped ratio varied from 1:9 to 9:1, both the methylene blue degradation rate and photocatalytic reaction rate initially increased before decreasing, while the half-life initially decreased before increasing. At a La[Formula: see text]–Mo[Formula: see text] co-doped ratio of 3:7, the photocatalytic activity of the TiO 2 nanotubes was optimal, achieving a maximum degradation rate of 89.73% within 8[Formula: see text]h — a 52% improvement over pure TiO 2 nanotubes.