DFT plus U Study of Molecular and Dissociative Water Adsorptions on the Fe3O4(110) Surface

Spin-polarized density functional theory method (GGA+U) and periodic supercell model have been used to study water adsorption properties on the Fe3O4(110) surface, which has A and B terminations in close surface energy. The adsorption of one and two water molecules is molecular on the A termination, while dissociative on the B termination. For the adsorption of three and four water molecules, mixed dissociative and molecular coadsorption is preferred on the A termination, and fully dissociative adsorption as well as mixed molecular and dissociative coadsorptions are preferred on the B terminations. The stepwise adsorption energies show that the full monolayer water adsorption on both terminations is thermodynamically possible. Further analysis shows that surface iron atoms and hydrogen bonding contribute to the adsorption energies. The adsorption mechanism has been analyzed on the basis of projected density of states (PDOS).