The reactivity of the anatase TiO2 (211) surface is systematically studied by ab initio calculations of the surface energy and water-adsorption energy. We find that anatase (211) has a high surface energy of 0.97 J/m2, close to that of the (001) surface, and the unsaturated fourfold-coordinated Ti4 atom is more reactive than the unsaturated fivefold-coordinated Ti5 atom. Accordingly, for water adsorption on the (211) surface, a dissociative form is favored on Ti4 sites, with a large adsorption energy ΔHH,OH∼1.28 eV, while a nondissociative molecular form is favored on Ti5 sites, with a smaller adsorption energy ΔHH2O∼0.78 eV. Such distinct surface properties lead to a mixed dissociative and molecular adsorption configuration when the coverage is increased from 1/3 to 1 monolayer. These results suggest that, similar to the (001) surface, the anatase (211) surface exhibits high reactivity and may be useful in catalytic and photocatalytic applications as well.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)