Surface treatment of hematite photoanodes with zinc acetate for water oxidation

A simple and inexpensive method to form a hematite photoanode for efficient water oxidation is reported. A very thin ZnO overlayer was deposited on top of a thin film of hematite and found, compared with non-treated hematite, to increase the photocurrent and reduce the onset potential for generating oxygen from water. After 3 cycles of ZnAc treatment, the photocurrent increased more than 40% to 1.08 mA cm−2 at 0.23 V vs. Ag/AgCl and onset potential for water oxidation shifted by −170 mV. It is proposed that the ZnO overlayer changes the flat band potential of hematite and reduces the surface defects.