Highly photostable palladium-loaded TiO2 nanotubes and the active species in the photodegradation of methyl orange

Highly photostable palladium-loaded TiO2 nanotubes (Pd/TNTs) were prepared by a simple photo-decomposition method and characterized by inductively coupled plasma, X-ray diffraction, UV-visible light diffuse reflectance spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, N2 adsorption-desorption, and photocurrent measurement. TEM images showed that the samples had a tubular structure. XPS results revealed that most of the palladium was present as Pd0. The photocatalytic performance was evaluated by monitoring the catalytic activity for the degradation of methyl orange solution under both UV and simulated sunlight irradiation. Pd/TNTs with 0.3 wt% Pd displayed higher activity than P25. The active species in the photocatalytic process were investigated by using different types of active species scavengers. hvb+ was the major reactive species in the photodegradation over the Pd/TNTs.