Water dissociative adsorption on the precovered Fe (100) surface from DFT computation

The H 2 O adsorption and dissociation on two kinds of the precovered Fe surface were studied by density functional theory. On the surface-1, the water molecules prefer to adsorb on the bridge and hollow sites than top sites, but there are no obvious preferred adsorption sites on the surface-2. The impurity energy difference and adsorption energy of the adsorbates are not sensitive to the adsorption orientation and height relative to the surface. Moreover, the Hirshfeld charge and the electronic density of state were analyzed. The rotation and dissociation of H 2 O molecules occur on the two kinds of precovered surfaces. Some H 2 O molecules are dissociated into OH and H groups. The energy barriers are from 0.4 to 1.0 eV which are consistent with the experimental data. H 2 O molecule can be dissociated more easily at the H a site on boron-precovered surface-1 than those on the phosphorus-precovered surface-1 and boron-precovered surface-2 due to the lower reaction barrier.