Adsorption of H2, Cl2, and HCl molecules on α-Cr2O3(0001) surfaces: A density functional theory investigation

Density functional theory calculations show that H2, Cl2, and HCl chemisorb dissociatively on the Cr2O3(0001) surface, which can be terminated by chromyl groups (Cr=O), Cr atoms, or O atoms. It is investigated that these molecules energetically prefer to adsorb dissociatively than in molecular form. Several dissociative adsorption sites have been considered for all the molecules on all the differently terminated surfaces and the corresponding adsorption energies are calculated. Dissociation energy barriers are estimated with the nudged elastic band method. Notable results from the dissociative adsorptions of Cl2 and H2 are the formation of a CrCl2 complex on the Cr terminated surface (a), and H2O complex on the O and the Cr=O terminated surfaces (b), and a H2O layer on the Cr=O terminated surface (b). Dissociative adsorption of HCl is less favored on the Cr=O and O terminated surfaces than on the Cr terminated surface.270