Preparation of cobalt coated TiO2 and WO3-TiO2 nanotube films via photo-assisted deposition with enhanced photocatalytic activity under visible light illumination

Highly ordered TiO2 and WO3-TiO2 nanotubes were prepared by one-step electrochemical anodizing method and cobalt has been successfully deposited on these nanotubes by photo-assisted deposition process. The morphology, crystal structure, elemental composition and light absorption capability of samples were characterized by field emission scanning electron microscope, X-ray diffraction, energy dispersive X-ray spectrometer and ultraviolet-visible spectroscopy methods. All cobalt loaded samples show an appearance of red shift relative to the unloaded samples. The degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of these novel visible-light-responsive photocatalysts. Results showed that the photocatalytic activity of bare WO3-TiO2 samples is higher than that with undoped TiO2 sample. Compared with unmodified TiO2 and WO3-TiO2, the Co/TiO2 and Co/WO3-TiO2 samples exhibited enhanced photocatalytic activity in the degradation of methylene blue. Kinetic research showed that the reaction rate constant of Co/WO3-TiO2 is approximately 2.26 times higher than the apparent reaction rate constant of bare WO3-TiO2. This work provides an insight into designing and synthesizing new TiO2-WO3 nanotubes-based hybrid materials for effective visible light-activated photocatalysis. The catalysts prepared in this study exhibit industrially relevant interests due to the low cost and high photocatalytic activity.