Effect of oxygen adsorption on structural and electronic properties of defective surfaces (0 0 1), (1 1 1), and (1 1 0) TiC: Ab initio study

A model of the oxygen adsorption on the defective surfaces (0 0 1), (1 1 1) and (1 1 0) of titanium carbide with different reconstructions is investigated by ab-initio calculations. In the framework of DFT calculations, the relaxed atomic structures of the surfaces (0 0 1), (1 1 1), and (1 1 0) of O/TixCy systems with titanium and carbon vacancies are studied. The structural and electronic properties of these systems are also investigated. The bond length and the adsorption energy for different reconstructions of the atomic structure of the surfaces (0 0 1), (1 1 1), and (1 1 0) of O/TixCy systems were established. The influence of the oxygen adatoms on the band structure and the electronic spectra of the O/TixCy system with different reconstructions was studied. Our calculations of effective charge per oxygen and nearest atoms show that the observed charge transfer from the titanium atoms to the oxygen and the carbon atoms is due to the reconstruction of local atomic and electronic structures and it correlates with processes of chemisorption. The physical nature and mechanisms of nanostructuring of the surfaces (0 0 1), (1 1 1) and (1 1 0) of titanium carbide are also discussed.