First-Principles Study of Photoinduced Water-Splitting on Fe2O3

Photoinduced water-splitting on hematite (Fe2O3) is investigated by first-principles calculations. (HO)(3)-Fe-H3O3-R, (HO)(3)-Fe-O-3-R, O-3-Fe-O-3-R, (HO)(3)-Fe-R and O-3-R terminations are considered, where R represents the bulk stacking sequence. The stability under photoelectrochemical conditions and the free energy of all reaction intermediates in a simple one-electron transfer reaction mechanism is calculated and the ability of different surface terminations to function as a photoanode is analyzed. Our results show that (i) under relevant photoelectrochemical conditions only O-3-Fe-O-3-R and O-3-R are stable and that (ii) the water-oxidation is only allowed on (HO)(3)-Fe-H3O3-R, (HO)(3)-Fe-O-3-R, O-3-Fe-O-3-R from thermodynamic considerations. The results suggest that hematite, as long as the (HO)(3)-Fe-H3O3-R termination is present under normal conditions, is a promising candidate for the photoanode.