Iron and Oxygen Vacancies at the Hematite Surface: Pristine Case and Chlorine Adatom
Defect complexes play critical roles on the dynamics of water molecules on photoelectrochemical devices. For the specific case of hematite (α-Fe2O3), iron and oxygen vacancies are said to mediated the water splitting process through the localization of optically-derived charges. Using first-principles methods based on the Density-Functional Theory we show that both iron and oxygen vacancies can be observed at the surface. For an oxygen-rich environment, usual under wet conditions, the charged iron vacancies should be more frequent. As sea water would be an ideal solvent for this kind of devices, we have also analyzed the effect of the additional chlorine adsorption on this surface. While chlorine adatom kills the charged oxygen vacancies, entering the void sites, it will not react with the iron vacancies, keeping them active during water splitting processes.