Synthesis and Characterization of Niobium-doped TiO2 Nanotube Arrays by Anodization of Ti-20Nb Alloys

Well crystallized niobium-doped TiO2 nanotube arrays (TiNbO-NT) were successfully synthesized via the anodization of titanium/niobium alloy sheets, followed with a heat treatment at 550 °C for 2 h. Morphology analysis results demonstrated that both the titanium/niobium alloy microstructure and the dissolution strength of electrolyte played major roles in the formation of nanotube structure. A single-phase microstructure was more favorable to the formation of uniform nanotube arrays, while modulating the dissolution strength of electrolyte was required to obtain nanotube arrays from the alloys with multi-phase microstructures. X-ray diffraction (XRD) and X-ray photoelectron (XPS) analysis results clearly demonstrated that niobium dopants (Nb5+) were successfully doped into TiO2 anatase lattice by substituting Ti4+ in this approach.