Tailoring surface states by sequential doping of Ti and Mg for kinetically enhanced hematite photoanode

Hematite (α-Fe₂O₃) is the most promising photoanode with a high theoretical photocurrent of 12.6 mA cm^-2. However, the photocurrent of Fe₂O₃ achieved now is far below its theoretical value, which is mainly due to its poor electronic conductivity and sluggish water oxidation kinetics. Herein, a co-doping method by sequential in-situ Ti-doping and ex-situ Mg-doping is used to tailor the surface states of Fe₂O₃ photoanode for great improvement of the charge transfer at the interface and the followed transport ability by the suppressed charge recombination, resulting in about 11-folds and 6.5 times higher than that of the undoped Fe₂O₃ and Ti:Fe₂O₃ at 1.23 V vs. RHE, respectively. This is mainly due to Mg and Ti-doping into Fe₂O₃ modifying the electrode surface states for more holes participation in water oxidation and better kinetics that enhanced charge transfer and suppressed charge recombination for the efficient water oxidation.