Natures of (001) and (101) surfaces of original and MnO2-loaded anatase: A comparative study

The (001) surface of TiO₂ is proved to be more active than the (101) surface in the SCR reaction while the roles of these two surfaces were still unclear. The present study carefully compared the adsorption characteristics of the (001) and (101) surfaces of original and MnO₂-loaded anatase by density functional theory calculations. The oxidizing ability and the feasibility of the oxygen vacancy formation were further explored. It was found that NH₃, NO, NO₂ and O₂ tended to adsorb on the (001) surface rather than on the (101) surface and the (001) surface was more oxidizing and was more prone to generate oxygen vacancies. Loading MnO₂ had a significant promotion on the performance of the (001) surface. The adsorption performance of the Mn(001) surface was much better than that of the Mn(101) surface. The limiting reactions for N₂ and H₂O production on the Mn(001) and Mn(101) surfaces were both the dissociation process of NH₃. The energy barriers of the SCR reaction on the Mn(001) surface were smaller than that on the Mn(101) surface, indicating that N₂ and H₂O formation on the Mn(001) surface was easier.