Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 65: Focus Session: Structure and Chemistry of Metal-Oxide Surfaces III

O 65.1: Talk

Wednesday, March 14, 2018, 15:00–15:15, MA 005

Density functional theory study of water and glycine adsorption at TiO2-TiN interfaces — •Julio Gutierrez Moreno and Michael Nolan — Tyndall National Institute, University College Cork

Titanium nitrite (TiN) is used in sensors as a conducting layer with good hardness and resistance to corrosion. TiN can spontaneously form a thin oxide layer when it is exposed to air, which could modify the properties of the coating and the impact on biofouling is not yet clear. Therefore, there is significant interest in studying the biofouling of oxidised TiN to find strategies to inhibit this process. In this work, we carried out Hubbard corrected density functional theory (DFT+U) simulations of the TiO2-TiN interface, as a model of the oxide layer on TiN. We investigate defects that can form during the oxide growth and are present after TiO2 formation such as Ti vacancies in TiN, O vacancies or the interdiffusion of O/N atoms within the interface. Our simulations show the formation of Ti3+ cations in the TiO2 that arise upon interface formation. We found that water adsorbs dissociatively on TiO2-TiN for low surface coverages while molecular adsorption is more stable are higher coverage. Glycine adsorption from gas phase is strong on the TiO2-TiN interface (E=-1.6 eV) compared to bare TiN (E=-0.4 eV). However the adherence of glycine is weaker on hydrated surfaces and also depends on the defects that might be present in the interface. The outcomes of these simulations give us a more comprehensive insight on the atomic level structure and the electronic properties of oxidised TiN surfaces and how this is related to biofouling.