Adsorption, Diffusion, and Dissociation of H 2 O on Kaolinite (001): a Density Functional Study

Density functional theory is used to investigate the adsorption, diffusion, and dissociation of H2O on kaolinite(001) surface. It is found that the preferred adsorption sites on the kaolinite(001) surface for H2O are the threefold hollow sites with the adsorption energies ranging from 1.06 to 1.15 eV. H2O does not adsorb on the six-fold hollow site of the aluminium(001) face of the third layer of kaolinite, implying that it is difficult for water molecules to penetrate the ideal kaolinite(001) surface. In addition, we calculate the energetic barriers for the diffusion of H2O between the most stable and next most stable adsorption sites, which range from 0.073 to 0.129eV. The results also show that H2O molecules are easy to diffuse on kaolinite(001) surface. Finally, our study indicates that no dissociation state exists for the H2O on kaolinite(001) surface.