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

Hematite (α-Fe2 O3 ) is the most promising photoanode with a high theoretical photocurrent of 12.6 mA cm-2 . However, the photocurrent of Fe2 O3 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 Fe2 O3 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 Fe2 O3 and Ti:Fe2 O3 at 1.23 V vs. RHE, respectively. This is mainly due to Mg and Ti-doping into Fe2 O3 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.