Anodic oxidation growth of lanthanum/manganese-doped TiO₂ nanotube arrays for photocatalytic degradation of various organic dyes

Lanthanum/manganese-doped TiO₂ nanotube arrays (La/Mn-TNAs) can provide a greater catalytic area and possess stronger photocatalytic activity than TiO₂ nanotubes (Li et al. in Nano Res 8(3):900–906, (2015)). Due to the wide band gap, TiO₂′s capacity to capture visible light is low, and TiO₂ (3.2 eV) can only absorb ultraviolet light. To resolve this issue, most researchers doped TiO₂ with nitrogen. In this paper, we doped transition metal ions and rare earth metal ions in TiO₂ nanotube arrays to decrease their band gaps, improving the activities of photocatalysts. In addition, La/Mn-TNAs were obtained by anodizing a Ti foil in the electrolyte. Additionally, the photocatalytic activity of the sample was evaluated by analyzing the degradation rate of organic pollutants. As a result, when the Ti foil was anodic oxidation for 3 h and contained 4.8 wt% of lanthanum and manganese, it could degrade organic dyes entirely in 60 min and the degradation rate of organic dyes was over 95%. Thus, La/Mn-TNAs can satisfy people’s requirement of rapid degradation of organic pollutants.