Oxygen vacancies as active sites for H2S dissociation on the rutile TiO2(110) surface: a first-principles study

Abstract

Spin-polarized DFT+U computations have been performed to investigate the role of oxygen vacancies in dissociating H₂S on the rutile TiO₂(110) surface. A bridged O_2c atom is demonstrated to be the most energetically favorable oxygen vacancy site, which makes V(O_2c) an electron donator center and induces an isolated defect level with narrowed band gaps. A H₂S molecule is adsorbed dissociatively over V(O_2c), but molecularly on the perfect surface. For H₂S dissociation, the HS/H intermediate state reveals the best thermal stability on both defected and perfect surfaces. Moreover, potential energy surface analysis shows that V(O_2c) reduces markedly the energy barriers for the paths along H₂S dissociation. This indicates oxygen vacancies to be efficient trap centers for H₂S dissociation, as evidenced by a significant interfacial charge transfer promoted by vacancies. This work could provide insights into the role of oxygen vacancies in facilitating the decomposition of H₂S on rutile TiO₂(110) surface.