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 H 2 O on kaolinite(001) surface. It is found that the preferred adsorption sites on the kaolinite(001) surface for H 2 O are the threefold hollow sites with the adsorption energies ranging from 1.06 to 1.15 eV. H 2 O 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 H 2 O between the most stable and next most stable adsorption sites, which range from 0.073 to 0.129eV. The results also show that H 2 O molecules are easy to diffuse on kaolinite(001) surface. Finally, our study indicates that no dissociation state exists for the H 2 O on kaolinite(001) surface.