Adsorption of Zn2+ at the rutile TiO2 (110)-aqueous interface was studied with Born-Oppenheimer molecular dynamics at 300 K. Simulations were carried out using the periodically repeated slab model with vacuum gap of 15 Å filled with 72 H2O molecules. Two possible adsorption sites, monodentate above bridging oxygen (Ti-O-Ti or Obr) and bidentate above terminal oxygens (Ti-O), were investigated. Sites with different coordination environment for adsorbed Zn2+ differ from each other by the position of Zn2+ above surface level and by characteristic Zn-O distances. Obtained results gave evidence that 4-fold coordination of adsorbed Zn2+ is more probable than the 6-fold coordination found for aqueous species. The hydrolysis of H2O molecules was observed in the first coordination shell of adsorbed ion, resulting in formation of OH- groups attached to Zn2+. Calculated energies favor the tetrahedral bidentate structure of hydrated Zn2+ on the rutile surface. The model structures are compared to observed positions of Zn2+ above the rutile (110) surface using X-ray scattering techniques.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Physical and Theoretical Chemistry