Physico-chemical properties of titania nanotubes synthesized via hydrothermal and annealing treatment

► Limited literature is available on the effects of annealing treatments on the physic-chemical properties of titania nanotubes (TNTs). Hence, this work is focused on the synthesis of titania nanotubes via hydrothermal and annealing routes. ► Annealing treatment does not damage the tubular structure of the samples. ► The crystallite size of the TNTs is larger and the degree of the crystallinity is higher after annealing process. Moreover, annealing treatment change the crystal structure from nanotubes to anatase phase, which is chemically and optically active. ► TNTs have larger specific surface areas, higher specific pore volumes and mean pore sizes than titania nanoparticles. ► In addition, annealing treatment red-shifts the absorption edge of TNTs and narrows their optical band gap width.