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

TitleDFT Investigation on the Electronic and Water Adsorption Properties of Pristine and N-Doped TiO2 Nanotubes for Photocatalytic Water Splitting Applications
Publication TypeJournal Article
Year of Publication2017
AuthorsEnriquez, John Isaac G., Moreno Joaquin Lorenzo V., David Melanie Y., Arboleda Nelson B., Lin Ong Hui, and Villagracia Al Rey C.
JournalJ. Electron. Mater.
Volume46
Pagination3592–3602
Date Published06/2017
ISSN0361-5235
KeywordsDensity functional theory, hydrogen, hydrogen production, photocatalyst, TiO2 Nanotube, water splitting
Abstract

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.

DOI10.1007/s11664-017-5342-y

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