DFT Investigation on the Electronic and Water Adsorption Properties of Pristine and N-Doped TiO2 Nanotubes for Photocatalytic Water Splitting Applications

• Main Authors: Enriquez, John Isaac G., Moreno, Joaquin Lorenzo V., David, Melanie Y., Arboleda, Nelson B., Lin, Ong Hui, Villagracia, Al Rey C.
• Format: text
• Published: Animo Repository 2017
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/837; https://animorepository.dlsu.edu.ph/context/faculty_research/article/1836/type/native/viewcontent
• Institution: De La Salle University

© 2017, The Minerals, Metals & Materials Society. Experimental studies have shown the production of hydrogen through a photocatalytic water splitting process using a titanium dioxide nanotube (TiO2NT) as a photoelectrode. In this study, a theoretical model of pristine and nitrogen-doped TiO2NT based on a TiO2 anatase (101) surface is presented. Spin unrestricted density functional theory calculations were performed to provide a detailed description of the geometries, electronic properties, and adsorption of water (H2O) on pristine and N-doped TiO2NT. The calculations show that doping with N will improve the photocatalytic properties of TiO2NT in two ways: First, the energy barrier of the dissociation reaction of water into hydroxyl radical and hydrogen atom is reduced; and second, the defect-induced states above the valence band lowers the band gap which will result in enhanced visible-light-driven photoactivity. Based on the position of the Fermi level relative to the defect induced energy levels, an optimal doping concentration of around 1.4% is proposed, which is in good agreement with experimental results. This study provides an atomic/molecular level understanding of the photocatalytic water splitting process and may serve as a groundwork for the rational design of more efficient photocatalysts.