Enhanced Light Response of Titania Nanotube Arrays Sensitized with Pyrite FeS2

Titania nanotube arrays were fabricated through anodic oxidation of Ti substrates in a glycol-based electrolyte and sensitized with pyrite FeS2 by using cathodic electrodeposition of Fe/Fe2O3 followed by sulfurizing with evaporative sulfur. The field emission scanning electron microscopy, X-ray diffraction, Raman, and XPS characterizations evidenced a successful sensitization of the nanotubes with ca. 3.8 wt% FeS2. The UV-Vis spectra confirmed the extension of the absorption edge to visible light for the titania nanotube arrays after the sensitization. The much-enhanced visible light response of the FeS2-sensitized film under the simulated solar light was revealed by the photocurrent and open-circuit potential measurements. Because of the high light-harvesting efficiency, the pyrite FeS2 is found to be an effective sensitizer for titania nanotube arrays to assist the photodegradation of rhodamine B in water under solar light illumination.