Molecular Adsorption of H2O on TiO2 and TiO2:Y Surfaces

TL;DR

This study uses density functional theory with van der Waals interactions to analyze water molecule adsorption on TiO2 surfaces, revealing stable configurations and effects on the material's electronic properties.

Contribution

It provides detailed insights into the adsorption energies, configurations, and electronic structure modifications of TiO2 surfaces due to water adsorption, incorporating dispersive interactions.

Findings

Adsorption energies range from -0.72 to -0.84 eV.

The most stable configuration involves water parallel to the Y axis.

Water adsorption decreases the band gap to 2.59 eV and introduces a new energy state.

Abstract

In this work, using theoretical calculations within the framework of the density functional theory, taking into account the dispersive VDW interaction, the processes of adsorption and interaction of a water molecule with a TiO2 surface in various configurations are investigated. At the atomic/molecular level, the interactions of a water molecule with a TiO2 surface have been studied for various orientations. The results of calculations within the framework of DFT+ VDW show that the adsorption energies of single water molecules in different initial positions on the substrate surface vary from-0.72 to-0.84 eV, and the most stable adsorbate structure is the TiO2+ H2O system upon adsorption of a molecule of water, parallel to the Y axis, because during the adsorption of H2O parallel to the Y axis, some favorable effects are observed in the band structure of titanium dioxide. On the one hand, the band gap decreases to 2.59 eV, and on the other hand, a new energy state appears in the band gap with an energy contribution of 0.17 eV, when water is physisorbed and interacts with a titanium atom at a distance of 2.12 {\AA} and occupies a perpendicular position relative to the surface.