Electrochemical synthesis of titania nanotube array for photoelectrochemical hydrogen production

摘要

Titanium dioxide (TiO_2) nanotube arrays have been extensively used during the last two decades for generating hydrogen by water photoelectrolysis and for many other applications involving photocatalysis, such as killing of bacteria, de-oderization, and gas sensors development. Several studies have reported the fabrication of nanotube arrays of different geometrical structures, with different length, inside diameter, and wall thickness. In this study, we report synthesis of TiO_2 photo-anodes with different nanotube geometries and the effect of the electrode surface structure on the generation of hydrogen. The nanotubular structures were produced by anodization and the tube structures were modified by varying anodization parameters such as electrolyte concentration, pH, voltage, and the time period of anodization. The surface of the nanotubular photo-anodes were then plasma treated with Helium (He) for removing contaminants and for reducing charge recombination sites followed by Nitrogen (N_2) plasma treatment for surface doping with N_2. The plasma surface treatment with N_2 was carried out for creating oxygen vacancies and for substitutional doping of N to treatment photo anodes bandgap at the surface. The results show that structural properties of nanotubular photoanodes and nitrogen plasma treatment have a significant effect on the photocurrent density.