Water Adsorption on a NiO(100) Surface: A GGA+U Study

First-principles density functional theory and supercell models are employed to calculate the adsorption of water molecules on the NiO(100) surface. Because the physical properties of NiO are effected by the strong on-site Coulomb repulsion between the 3d electrons, the electronic correlations are also taken into account in the form of GGA+U. Possible initial adsorption configurations for the H2O/NiO(100) system were investigated; it was found that the configuration of the water molecule parallel to the surface was energetically favorable. The electronic properties, magnetic properties, and work function were also studied. The calculation results showed that if molecularly adsorbed, the water molecule would prefer to bond via oxygen at the Ni site on the NiO(100) surface, and the work functions linearly decreased with the coverage increase. The present GGA+U study is in excellent agreement with experimental observations.