Investigation of the wetting of transition metal-oxide surfaces
Title: Investigation of the wetting of transition metal-oxide surfaces
DNr: SNIC 2015/1-138
Project Type: SNIC Medium Compute
Principal Investigator: Anders Sandell <anders.sandell@physics.uu.se>
Affiliation: Uppsala universitet
Duration: 2015-04-29 – 2016-05-01
Classification: 10302
Keywords:

Abstract

Titanium dioxide is a important material for a wide range of applications,such as photochemical reactions (water splitting), dye-sensitized solar cells, active substrates for nano-catalysis, gas sensing, and biomedical implants. Rutile and anatase titanium dioxide surfaces are widely used systems, for fundamental studies of reducible metal-oxide surface chemistry as well as in different technologies, mentioned above. Water molecules are omnipresent in most working environments, especially under atmospheric conditions. Earlier theoretical and experimental results gave a good description of the lower coverage limit (~0.25 monolayers of adsorbed water molecules) and the full monolayer. The actual growth mechanism from isolated adsorbed species to the full first monolayer, on the other hand, is still not sufficiently understood yet. On an atomic level this growth is governed by a complex interplay of hydrogen bond networks of the adsorbates and their interaction with the oxide surface. We are employing state-of-the-art experimental techniques, such as x-ray photoelectron spectroscopy and scanning tunneling microscopy, to monitor the growth of the first molecular monolayers on different pristine and defective oxide surfaces. It allowed us to suggest a mechanism of first monolayer formation [J.Phys.Chem. C 117, 17078 (2013)], however, the kinetic aspects of this formation are still unclear. By means of state-of-the-art implementations of density functional theory in combination with kinetic Monte-Carlo simulations we will continue to investigate adsorption, dissociation, mobility and clustering of water molecules on titania surfaces. Our calculations will provide us with the necessary accurate electronic, structural, and kinetic information of the water - transition metal oxide system. Especially, the complementary insights into the complex physics of the water - TiO2 interaction will allow us to achieve a comprehensive explanation of this complex surface science problem. Based on our experiences and knowledge of this system, we are in an advantages position to address similar surface science problems and to draw obtain general conclusions.