Adsorption behavior of Cl2 on TiC0.89O0.11(001) surface based on the first principle calculation

Abstract

Based on the first-principles ab initio calculation method of density functional theory (DFT), the adsorption models of Cl₂ molecules on both the TiC_0.89O_0.11(001) intact surface and the carbon vacancy surface were established, followed by calculations and analysis of the adsorption structures, adsorption energy, differential charge density, and density of states (DOS). The results demonstrate that the adsorption process of Cl₂ molecules on the TiC_0.89O_0.11(001) surface involves chemical adsorption, with a higher likelihood of dissociation into Cl atoms during adsorption. These dissociated Cl atoms can potentially interact with surface Ti and/or C atoms to form Ti-Cl bonds, C-Cl bonds, Ti-Cl-C bonds, and Ti-Cl-Ti bonds. Simultaneously, the stability of the adsorbed structure is influenced by both the bonding conditions between Cl atoms and surface atoms and the position of Cl atom adsorption (e.g., whether it is located above the vacancy C). Following adsorption, there is a weakening in the bonding strength of Ti-C or Ti-O bonds on the TiC_0.89O_0.11(001) surface. During the adsorption process, Cl atoms can either act as electron donors or acceptors. When the Ti-Cl bond structure is formed, Cl atoms function as electron acceptors; however, when the C-Cl bond structure is established, Cl atoms predominantly act as electron donors. Surface Ti atoms act as electron donors while surface C and O atoms function as electron acceptors. Additionally, the presence of surface carbon vacancy enhances the interaction between Cl and Ti atoms, weakens the interaction between Cl and C atoms, and attenuates the interaction between C, O, and Ti atoms in the structure. And it can augment the electron acquisition by Cl₂ molecules upon adsorption, reduce the adsorption energy, and promote greater stability in the adsorption structure. All the effects contribute to facilitating TiCl₄ formation.