Cobalt Oxide Modified Highly Ordered TiO₂ Nanotube Arrays: Enhanced Visible Light Photoelectrochemical Properties

Highly aligned TiO₂nanotube arrays (NTs) modified by cobalt oxide nanoparticles were prepared by one-step electrochemical anodization of Ti foil using Co(NO₃)₂˙6H₂O as cobalt source and subsequent thermal treatment in air at 450 °C for 2 h. Their morphology, structure and optical properties were investigated by field emission scanning electron microscope, energy dispersion spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV-visible reflectance spectroscopy. The photoelectrochemical properties were investigated by the photocurrent response under the irradiation of the simulated sunlight at room temperature. The results showed that the photocurrent response of the TiO₂ NTs modified by cobalt oxide is higher than that of the unmodified TiO₂ NTs, which may be ascribed to faster electron transport and more efficient separation of the photogenerated holes and electrons in the cobalt oxide anchored TiO₂ NTs. The results presented here demonstrate that the TiO₂ NTs modified by cobalt oxide might have an important application in solar cells or photocatalysis owing to its efficient utilization of visible light.