Electro-oxidation of water on hematite: Effects of surface termination and oxygen vacancies investigated by first-principles.

The oxygen evolution reaction on hydroxyl- and oxygen-terminated hematite was investigated using first-principle calcns. within a theor. electrochem. framework. Both pristine hematite and hematite contg. oxygen vacancies were considered. The onset potential was detd. to be 1.79 V and 2.09 V vs. the reversible hydrogen electrode (RHE) for the pristine hydroxyl- and oxygen-terminated hematite, resp. The presence of oxygen vacancies in the hematite surface resulted in pronounced shifts of the onset potential to 3.09 V and 1.83 V, resp. Electrochem. oxidn. measurements conducted on thin-film hematite anodes, resulted in a measured onset potential of 1.66 V vs. RHE. Furthermore, the threshold potential between the hydroxyl- and oxygen-terminated hematite was detd. as a function of pH. The results indicate that electrochem. water oxidn. on hematite occurs on the oxygen-terminated hematite, contg. oxygen vacancies. [on SciFinder(R)]