The structure and energetics of thin water overlayers on the (101) surface of TiO 2-anatase have been studied through first-principles molecular dynamics simulations at T = 160 K. At one monolayer coverage, H 2O molecules are adsorbed at the 5-fold Ti sites (Ti 5c), forming an ordered crystal-like 2D layer with no significant water-water interactions. For an adsorbed bilayer, H 2O molecules at both Ti 5c and bridging oxygen (O 2c) sites form a partially ordered structure, where the water oxygens occupy regular sites but the orientation of the molecules is disordered; in addition, stress-relieving defects are usually present. When a third layer is adsorbed, very limited parallel and perpendicular order is observed above the first bilayer. The calculated energetics of multilayer adsorption is in good agreement with recent temperature-programmed desorption data.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces