Effect of the preparation conditions on the performance of TiO2 nanotube arrays obtained by electrochemical oxidation

In this paper, nanotubular arrays of TiO2 are used as anode in an undivided electrochemical cell where the water photosplitting process may occur enhanced by the external applied potential. The behavior of the nanotubular structure, prepared by electrochemical anodization of Ti foils, is investigated. All the samples were submitted to thermal annealing in order to transform the amorphous structure into crystalline. Emphasis is paid on the influence of the current transient during the anodization on the photochemical response of the samples. Depending on the current transient, a different distribution of defects, at the surface or in the bulk, is originated in the initial structure, which resulted differently sensitive to the temperature.

► Nanotubular arrays of TiO2 obtained by Ti foil anodization, are effective in the process of photoelectrochemical splitting of water.
► A combined effect of the current anodization transient and the annealing T determines the nature and distribution of defects in the structure.
► The resulting distribution of defects in the samples has been correlated to the final response of the nanotubular structures.