Reduced N/Ni-doped TiO2 nanotubes photoanodes for photoelectrochemical water splitting

Abstract

This work reports the facile synthesis of reduced N/Ni-doped TiO₂ nanotubes photoanodes and their photocatalytic activity application. The obtained photoanodes were characterized by scanning electron microscope (SEM), Raman spectrum (Raman), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance absorption spectra. The narrowed band gap of TiO₂ due to the doping of N and Ni elements could enhance the light absorption effectively. The NaBH₄ reduction process resulted in the formation of oxygen vacancies in photoanodes. The electrochemical characterization revealed that photo-induced carriers were more efficient charge separation and transportation in reduced N/Ni-doped TiO₂ nanotubes photoanodes. The highest photocurrent density obtained from reduced N/Ni-doped TiO₂ nanotubes photoanodes was 2.52 mA cm⁻² at 0 V vs. Ag/AgCl in 1 M KOH solution, which was about five times as high as that obtained from undoped TiO₂.