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Ion-exchangeable titanate nanotubes with visible light responsive photocatalytic activities for dyes degradation.

Sn(2+)- and Pb(2+)-substituted NaHTi3O7 nanotubes were prepared by a hydrothermal synthesis method followed by ion-exchange reaction. The samples were characterized by XRD, SEM, TEM, XPS and UV-visible diffuse reflectance spectroscopy. The photocatalytic activities were investigated for the photodegradation of methylene orange (MO) and methylene blue (MB) under visible light irradiation. The results indicate that Sn2+ and Pb2+ substitutions could have significant impacts on the optical properties and photocatalytic activities of samples. Both Sn(2+)- and Pb(2+)-substituted NaHTi3O7 nanotubes show activities for methylene orange and methylene blue photodegradation under visible light irradiation. With better absorption of visible light, the Sn-NaHTi3O7 sample showed higher activity than Pb-NaHTi3O7.