Adsorption-desorption of F2 diatomic molecule on Ti (100) surface at different coverages

Abstract

Fluorine molecules and ions are used as an etchant for metal surface processing. The presence of fluorine significantly influences the electrochemical behaviour on a metal surface, which has major relevance for etching, corrosion, electro-catalysis and galvanic deposition processes. Although the fluorine ions play an important role in metal surface etching, the studies remain limited and unclear, especially at the atomistic scale. In this work, density functional theory is used to investigate the structural and electronic properties of F₂ diatomic molecule adsorption on Ti (100) surface at different coverages. Results revealed a dissociative adsorption mechanism of F₂ on the Ti (100) surface. Adsorption energy analysis of F₂ on Ti (100) surface denotes an exothermic process. Moreover, increasing F₂ coverage resulted in the formation of TiF₄ and Ti₂F₆ molecules on the surface. In addition, the calculated heat of formation for TiF₄ was found to be more favourable than Ti₂F₆ species. Calculated desorption energies for TiF₄ and Ti₂F₆ is 11.73 eV/atom and 9.04 eV/atom, suggesting non-spontaneous.