Structural Characterization and Visible Light-Induced Photoelectrochemical Performance of Fe-Sensitized TiO2 Nanotube Arrays Prepared via Electrodeposition

Abstract

Surface modification of TiO2 nanotube arrays via metal doping is one of the approaches to \nnarrow the wide bandgap of TiO2 in order to increase its adsorption to the visible region. \nThe present work focuses on the fabrication of a Fe-sensitized TiO2 nanotube arrays (Fe- \nTNT) photoanode. Ordered Fe-TNTs were successfully synthesized using a facile two-step \nelectrochemical method by varying the deposition voltage (2-4 V). The morphology, \nstructure, composition, and visible light response were characterized by field-emission \nscanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray \nspectroscopy (EDX), UV-Vis diffusion reflection spectroscopy (DRS), and \nphotoelectrochemical (PEC) test. The XRD investigation demonstrated that the sensitization \nof Fe did not destroy the nanotube array structure, and the Fe-TNTs had an anatase phase \ncomposed of cubic-like particles at higher deposition voltages. The UV–Vis absorption \nspectra of the Fe-TNTs showed a redshift of photoresponse towards visible light. Such a \nredshift was characterized by a decrease in bandgap energy and the photo efficiency was \nenhanced. The optimal photoelectrochemical performance was observed at 2.5 V deposition \nvoltage for 10 minutes and surpassed that of pristine titania nanotube arrays. The present \nwork demonstrates feasible modification of TiO2 with Fe as a potential photoanode in solar \nconversion devices.