Photodegradation of methylene blue over a new down-shifting luminescence catalyst

TiO $$₂$$ nanotube arrays prepared by anodization technology are modified with a samarium ion (Sm $$³⁺)$$ by a hydrothermal method for use in photodegradation of methylene blue (MB). The samarium ion as a down-shifting luminescence material can improve UV radiation harvesting to increase visible light utilization. The efficiency of the photocatalytic activity for the modified-TiO $$₂$$ nanotube arrays in degradation of MB was investigated under UV–Vis light irradiation. The results show that Sm–TiO $$₂$$ nanotubes can increase the photocatalytic efficiency of MB. When TiO $$₂$$ nanotubes are modified by 0.02 M Sm $$³⁺$$ , MB can be almost completely degraded when compared with bare TiO $$₂$$ nanotubes. This indicates that TiO $$₂$$ nanotubes structure, surface area and good UV radiation harvesting play important roles in the degradation of MB.